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2018-12-28kasan: add hooks implementation for tag-based modeAndrey Konovalov3-19/+153
This commit adds tag-based KASAN specific hooks implementation and adjusts common generic and tag-based KASAN ones. 1. When a new slab cache is created, tag-based KASAN rounds up the size of the objects in this cache to KASAN_SHADOW_SCALE_SIZE (== 16). 2. On each kmalloc tag-based KASAN generates a random tag, sets the shadow memory, that corresponds to this object to this tag, and embeds this tag value into the top byte of the returned pointer. 3. On each kfree tag-based KASAN poisons the shadow memory with a random tag to allow detection of use-after-free bugs. The rest of the logic of the hook implementation is very much similar to the one provided by generic KASAN. Tag-based KASAN saves allocation and free stack metadata to the slab object the same way generic KASAN does. Link: http://lkml.kernel.org/r/bda78069e3b8422039794050ddcb2d53d053ed41.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28mm: move obj_to_index to include/linux/slab_def.hAndrey Konovalov1-13/+0
While with SLUB we can actually preassign tags for caches with contructors and store them in pointers in the freelist, SLAB doesn't allow that since the freelist is stored as an array of indexes, so there are no pointers to store the tags. Instead we compute the tag twice, once when a slab is created before calling the constructor and then again each time when an object is allocated with kmalloc. Tag is computed simply by taking the lowest byte of the index that corresponds to the object. However in kasan_kmalloc we only have access to the objects pointer, so we need a way to find out which index this object corresponds to. This patch moves obj_to_index from slab.c to include/linux/slab_def.h to be reused by KASAN. Link: http://lkml.kernel.org/r/c02cd9e574cfd93858e43ac94b05e38f891fef64.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28kasan: add bug reporting routines for tag-based modeAndrey Konovalov4-37/+59
This commit adds rountines, that print tag-based KASAN error reports. Those are quite similar to generic KASAN, the difference is: 1. The way tag-based KASAN finds the first bad shadow cell (with a mismatching tag). Tag-based KASAN compares memory tags from the shadow memory to the pointer tag. 2. Tag-based KASAN reports all bugs with the "KASAN: invalid-access" header. Also simplify generic KASAN find_first_bad_addr. Link: http://lkml.kernel.org/r/aee6897b1bd077732a315fd84c6b4f234dbfdfcb.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28kasan: split out generic_report.c from report.cAndrey Konovalov5-185/+257
Move generic KASAN specific error reporting routines to generic_report.c without any functional changes, leaving common error reporting code in report.c to be later reused by tag-based KASAN. Link: http://lkml.kernel.org/r/ba48c32f8e5aefedee78998ccff0413bee9e0f5b.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28kasan, mm: perform untagged pointers comparison in kreallocAndrey Konovalov1-1/+1
The krealloc function checks where the same buffer was reused or a new one allocated by comparing kernel pointers. Tag-based KASAN changes memory tag on the krealloc'ed chunk of memory and therefore also changes the pointer tag of the returned pointer. Therefore we need to perform comparison on untagged (with tags reset) pointers to check whether it's the same memory region or not. Link: http://lkml.kernel.org/r/14f6190d7846186a3506cd66d82446646fe65090.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28kasan: preassign tags to objects with ctors or SLAB_TYPESAFE_BY_RCUAndrey Konovalov2-11/+15
An object constructor can initialize pointers within this objects based on the address of the object. Since the object address might be tagged, we need to assign a tag before calling constructor. The implemented approach is to assign tags to objects with constructors when a slab is allocated and call constructors once as usual. The downside is that such object would always have the same tag when it is reallocated, so we won't catch use-after-frees on it. Also pressign tags for objects from SLAB_TYPESAFE_BY_RCU caches, since they can be validy accessed after having been freed. Link: http://lkml.kernel.org/r/f158a8a74a031d66f0a9398a5b0ed453c37ba09a.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28kasan: add tag related helper functionsAndrey Konovalov2-0/+68
This commit adds a few helper functions, that are meant to be used to work with tags embedded in the top byte of kernel pointers: to set, to get or to reset the top byte. Link: http://lkml.kernel.org/r/f6c6437bb8e143bc44f42c3c259c62e734be7935.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Christoph Lameter <cl@linux.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28kasan: initialize shadow to 0xff for tag-based modeAndrey Konovalov1-1/+2
A tag-based KASAN shadow memory cell contains a memory tag, that corresponds to the tag in the top byte of the pointer, that points to that memory. The native top byte value of kernel pointers is 0xff, so with tag-based KASAN we need to initialize shadow memory to 0xff. [cai@lca.pw: arm64: skip kmemleak for KASAN again\ Link: http://lkml.kernel.org/r/20181226020550.63712-1-cai@lca.pw Link: http://lkml.kernel.org/r/5cc1b789aad7c99cf4f3ec5b328b147ad53edb40.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28kasan: rename kasan_zero_page to kasan_early_shadow_pageAndrey Konovalov1-30/+40
With tag based KASAN mode the early shadow value is 0xff and not 0x00, so this patch renames kasan_zero_(page|pte|pmd|pud|p4d) to kasan_early_shadow_(page|pte|pmd|pud|p4d) to avoid confusion. Link: http://lkml.kernel.org/r/3fed313280ebf4f88645f5b89ccbc066d320e177.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Suggested-by: Mark Rutland <mark.rutland@arm.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Christoph Lameter <cl@linux.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28kasan: add CONFIG_KASAN_GENERIC and CONFIG_KASAN_SW_TAGSAndrey Konovalov5-4/+84
This commit splits the current CONFIG_KASAN config option into two: 1. CONFIG_KASAN_GENERIC, that enables the generic KASAN mode (the one that exists now); 2. CONFIG_KASAN_SW_TAGS, that enables the software tag-based KASAN mode. The name CONFIG_KASAN_SW_TAGS is chosen as in the future we will have another hardware tag-based KASAN mode, that will rely on hardware memory tagging support in arm64. With CONFIG_KASAN_SW_TAGS enabled, compiler options are changed to instrument kernel files with -fsantize=kernel-hwaddress (except the ones for which KASAN_SANITIZE := n is set). Both CONFIG_KASAN_GENERIC and CONFIG_KASAN_SW_TAGS support both CONFIG_KASAN_INLINE and CONFIG_KASAN_OUTLINE instrumentation modes. This commit also adds empty placeholder (for now) implementation of tag-based KASAN specific hooks inserted by the compiler and adjusts common hooks implementation. While this commit adds the CONFIG_KASAN_SW_TAGS config option, this option is not selectable, as it depends on HAVE_ARCH_KASAN_SW_TAGS, which we will enable once all the infrastracture code has been added. Link: http://lkml.kernel.org/r/b2550106eb8a68b10fefbabce820910b115aa853.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28kasan: rename source files to reflect the new naming schemeAndrey Konovalov3-4/+4
We now have two KASAN modes: generic KASAN and tag-based KASAN. Rename kasan.c to generic.c to reflect that. Also rename kasan_init.c to init.c as it contains initialization code for both KASAN modes. Link: http://lkml.kernel.org/r/88c6fd2a883e459e6242030497230e5fb0d44d44.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28kasan: move common generic and tag-based code to common.cAndrey Konovalov4-569/+614
Tag-based KASAN reuses a significant part of the generic KASAN code, so move the common parts to common.c without any functional changes. Link: http://lkml.kernel.org/r/114064d002356e03bb8cc91f7835e20dc61b51d9.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28kasan, slub: handle pointer tags in early_kmem_cache_node_allocAndrey Konovalov1-5/+5
The previous patch updated KASAN hooks signatures and their usage in SLAB and SLUB code, except for the early_kmem_cache_node_alloc function. This patch handles that function separately, as it requires to reorder some of the initialization code to correctly propagate a tagged pointer in case a tag is assigned by kasan_kmalloc. Link: http://lkml.kernel.org/r/fc8d0fdcf733a7a52e8d0daaa650f4736a57de8c.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Christoph Lameter <cl@linux.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28kasan, mm: change hooks signaturesAndrey Konovalov5-29/+34
Patch series "kasan: add software tag-based mode for arm64", v13. This patchset adds a new software tag-based mode to KASAN [1]. (Initially this mode was called KHWASAN, but it got renamed, see the naming rationale at the end of this section). The plan is to implement HWASan [2] for the kernel with the incentive, that it's going to have comparable to KASAN performance, but in the same time consume much less memory, trading that off for somewhat imprecise bug detection and being supported only for arm64. The underlying ideas of the approach used by software tag-based KASAN are: 1. By using the Top Byte Ignore (TBI) arm64 CPU feature, we can store pointer tags in the top byte of each kernel pointer. 2. Using shadow memory, we can store memory tags for each chunk of kernel memory. 3. On each memory allocation, we can generate a random tag, embed it into the returned pointer and set the memory tags that correspond to this chunk of memory to the same value. 4. By using compiler instrumentation, before each memory access we can add a check that the pointer tag matches the tag of the memory that is being accessed. 5. On a tag mismatch we report an error. With this patchset the existing KASAN mode gets renamed to generic KASAN, with the word "generic" meaning that the implementation can be supported by any architecture as it is purely software. The new mode this patchset adds is called software tag-based KASAN. The word "tag-based" refers to the fact that this mode uses tags embedded into the top byte of kernel pointers and the TBI arm64 CPU feature that allows to dereference such pointers. The word "software" here means that shadow memory manipulation and tag checking on pointer dereference is done in software. As it is the only tag-based implementation right now, "software tag-based" KASAN is sometimes referred to as simply "tag-based" in this patchset. A potential expansion of this mode is a hardware tag-based mode, which would use hardware memory tagging support (announced by Arm [3]) instead of compiler instrumentation and manual shadow memory manipulation. Same as generic KASAN, software tag-based KASAN is strictly a debugging feature. [1] https://www.kernel.org/doc/html/latest/dev-tools/kasan.html [2] http://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html [3] https://community.arm.com/processors/b/blog/posts/arm-a-profile-architecture-2018-developments-armv85a ====== Rationale On mobile devices generic KASAN's memory usage is significant problem. One of the main reasons to have tag-based KASAN is to be able to perform a similar set of checks as the generic one does, but with lower memory requirements. Comment from Vishwath Mohan <vishwath@google.com>: I don't have data on-hand, but anecdotally both ASAN and KASAN have proven problematic to enable for environments that don't tolerate the increased memory pressure well. This includes (a) Low-memory form factors - Wear, TV, Things, lower-tier phones like Go, (c) Connected components like Pixel's visual core [1]. These are both places I'd love to have a low(er) memory footprint option at my disposal. Comment from Evgenii Stepanov <eugenis@google.com>: Looking at a live Android device under load, slab (according to /proc/meminfo) + kernel stack take 8-10% available RAM (~350MB). KASAN's overhead of 2x - 3x on top of it is not insignificant. Not having this overhead enables near-production use - ex. running KASAN/KHWASAN kernel on a personal, daily-use device to catch bugs that do not reproduce in test configuration. These are the ones that often cost the most engineering time to track down. CPU overhead is bad, but generally tolerable. RAM is critical, in our experience. Once it gets low enough, OOM-killer makes your life miserable. [1] https://www.blog.google/products/pixel/pixel-visual-core-image-processing-and-machine-learning-pixel-2/ ====== Technical details Software tag-based KASAN mode is implemented in a very similar way to the generic one. This patchset essentially does the following: 1. TCR_TBI1 is set to enable Top Byte Ignore. 2. Shadow memory is used (with a different scale, 1:16, so each shadow byte corresponds to 16 bytes of kernel memory) to store memory tags. 3. All slab objects are aligned to shadow scale, which is 16 bytes. 4. All pointers returned from the slab allocator are tagged with a random tag and the corresponding shadow memory is poisoned with the same value. 5. Compiler instrumentation is used to insert tag checks. Either by calling callbacks or by inlining them (CONFIG_KASAN_OUTLINE and CONFIG_KASAN_INLINE flags are reused). 6. When a tag mismatch is detected in callback instrumentation mode KASAN simply prints a bug report. In case of inline instrumentation, clang inserts a brk instruction, and KASAN has it's own brk handler, which reports the bug. 7. The memory in between slab objects is marked with a reserved tag, and acts as a redzone. 8. When a slab object is freed it's marked with a reserved tag. Bug detection is imprecise for two reasons: 1. We won't catch some small out-of-bounds accesses, that fall into the same shadow cell, as the last byte of a slab object. 2. We only have 1 byte to store tags, which means we have a 1/256 probability of a tag match for an incorrect access (actually even slightly less due to reserved tag values). Despite that there's a particular type of bugs that tag-based KASAN can detect compared to generic KASAN: use-after-free after the object has been allocated by someone else. ====== Testing Some kernel developers voiced a concern that changing the top byte of kernel pointers may lead to subtle bugs that are difficult to discover. To address this concern deliberate testing has been performed. It doesn't seem feasible to do some kind of static checking to find potential issues with pointer tagging, so a dynamic approach was taken. All pointer comparisons/subtractions have been instrumented in an LLVM compiler pass and a kernel module that would print a bug report whenever two pointers with different tags are being compared/subtracted (ignoring comparisons with NULL pointers and with pointers obtained by casting an error code to a pointer type) has been used. Then the kernel has been booted in QEMU and on an Odroid C2 board and syzkaller has been run. This yielded the following results. The two places that look interesting are: is_vmalloc_addr in include/linux/mm.h is_kernel_rodata in mm/util.c Here we compare a pointer with some fixed untagged values to make sure that the pointer lies in a particular part of the kernel address space. Since tag-based KASAN doesn't add tags to pointers that belong to rodata or vmalloc regions, this should work as is. To make sure debug checks to those two functions that check that the result doesn't change whether we operate on pointers with or without untagging has been added. A few other cases that don't look that interesting: Comparing pointers to achieve unique sorting order of pointee objects (e.g. sorting locks addresses before performing a double lock): tty_ldisc_lock_pair_timeout in drivers/tty/tty_ldisc.c pipe_double_lock in fs/pipe.c unix_state_double_lock in net/unix/af_unix.c lock_two_nondirectories in fs/inode.c mutex_lock_double in kernel/events/core.c ep_cmp_ffd in fs/eventpoll.c fsnotify_compare_groups fs/notify/mark.c Nothing needs to be done here, since the tags embedded into pointers don't change, so the sorting order would still be unique. Checks that a pointer belongs to some particular allocation: is_sibling_entry in lib/radix-tree.c object_is_on_stack in include/linux/sched/task_stack.h Nothing needs to be done here either, since two pointers can only belong to the same allocation if they have the same tag. Overall, since the kernel boots and works, there are no critical bugs. As for the rest, the traditional kernel testing way (use until fails) is the only one that looks feasible. Another point here is that tag-based KASAN is available under a separate config option that needs to be deliberately enabled. Even though it might be used in a "near-production" environment to find bugs that are not found during fuzzing or running tests, it is still a debug tool. ====== Benchmarks The following numbers were collected on Odroid C2 board. Both generic and tag-based KASAN were used in inline instrumentation mode. Boot time [1]: * ~1.7 sec for clean kernel * ~5.0 sec for generic KASAN * ~5.0 sec for tag-based KASAN Network performance [2]: * 8.33 Gbits/sec for clean kernel * 3.17 Gbits/sec for generic KASAN * 2.85 Gbits/sec for tag-based KASAN Slab memory usage after boot [3]: * ~40 kb for clean kernel * ~105 kb (~260% overhead) for generic KASAN * ~47 kb (~20% overhead) for tag-based KASAN KASAN memory overhead consists of three main parts: 1. Increased slab memory usage due to redzones. 2. Shadow memory (the whole reserved once during boot). 3. Quaratine (grows gradually until some preset limit; the more the limit, the more the chance to detect a use-after-free). Comparing tag-based vs generic KASAN for each of these points: 1. 20% vs 260% overhead. 2. 1/16th vs 1/8th of physical memory. 3. Tag-based KASAN doesn't require quarantine. [1] Time before the ext4 driver is initialized. [2] Measured as `iperf -s & iperf -c 127.0.0.1 -t 30`. [3] Measured as `cat /proc/meminfo | grep Slab`. ====== Some notes A few notes: 1. The patchset can be found here: https://github.com/xairy/kasan-prototype/tree/khwasan 2. Building requires a recent Clang version (7.0.0 or later). 3. Stack instrumentation is not supported yet and will be added later. This patch (of 25): Tag-based KASAN changes the value of the top byte of pointers returned from the kernel allocation functions (such as kmalloc). This patch updates KASAN hooks signatures and their usage in SLAB and SLUB code to reflect that. Link: http://lkml.kernel.org/r/aec2b5e3973781ff8a6bb6760f8543643202c451.1544099024.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Cc: Christoph Lameter <cl@linux.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-27Merge branch 'core-rcu-for-linus' of ↵Linus Torvalds5-10/+9
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull RCU updates from Ingo Molnar: "The biggest RCU changes in this cycle were: - Convert RCU's BUG_ON() and similar calls to WARN_ON() and similar. - Replace calls of RCU-bh and RCU-sched update-side functions to their vanilla RCU counterparts. This series is a step towards complete removal of the RCU-bh and RCU-sched update-side functions. ( Note that some of these conversions are going upstream via their respective maintainers. ) - Documentation updates, including a number of flavor-consolidation updates from Joel Fernandes. - Miscellaneous fixes. - Automate generation of the initrd filesystem used for rcutorture testing. - Convert spin_is_locked() assertions to instead use lockdep. ( Note that some of these conversions are going upstream via their respective maintainers. ) - SRCU updates, especially including a fix from Dennis Krein for a bag-on-head-class bug. - RCU torture-test updates" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (112 commits) rcutorture: Don't do busted forward-progress testing rcutorture: Use 100ms buckets for forward-progress callback histograms rcutorture: Recover from OOM during forward-progress tests rcutorture: Print forward-progress test age upon failure rcutorture: Print time since GP end upon forward-progress failure rcutorture: Print histogram of CB invocation at OOM time rcutorture: Print GP age upon forward-progress failure rcu: Print per-CPU callback counts for forward-progress failures rcu: Account for nocb-CPU callback counts in RCU CPU stall warnings rcutorture: Dump grace-period diagnostics upon forward-progress OOM rcutorture: Prepare for asynchronous access to rcu_fwd_startat torture: Remove unnecessary "ret" variables rcutorture: Affinity forward-progress test to avoid housekeeping CPUs rcutorture: Break up too-long rcu_torture_fwd_prog() function rcutorture: Remove cbflood facility torture: Bring any extra CPUs online during kernel startup rcutorture: Add call_rcu() flooding forward-progress tests rcutorture/formal: Replace synchronize_sched() with synchronize_rcu() tools/kernel.h: Replace synchronize_sched() with synchronize_rcu() net/decnet: Replace rcu_barrier_bh() with rcu_barrier() ...
2018-12-26Merge tag 'arm64-upstream' of ↵Linus Torvalds1-7/+18
git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux Pull arm64 festive updates from Will Deacon: "In the end, we ended up with quite a lot more than I expected: - Support for ARMv8.3 Pointer Authentication in userspace (CRIU and kernel-side support to come later) - Support for per-thread stack canaries, pending an update to GCC that is currently undergoing review - Support for kexec_file_load(), which permits secure boot of a kexec payload but also happens to improve the performance of kexec dramatically because we can avoid the sucky purgatory code from userspace. Kdump will come later (requires updates to libfdt). - Optimisation of our dynamic CPU feature framework, so that all detected features are enabled via a single stop_machine() invocation - KPTI whitelisting of Cortex-A CPUs unaffected by Meltdown, so that they can benefit from global TLB entries when KASLR is not in use - 52-bit virtual addressing for userspace (kernel remains 48-bit) - Patch in LSE atomics for per-cpu atomic operations - Custom preempt.h implementation to avoid unconditional calls to preempt_schedule() from preempt_enable() - Support for the new 'SB' Speculation Barrier instruction - Vectorised implementation of XOR checksumming and CRC32 optimisations - Workaround for Cortex-A76 erratum #1165522 - Improved compatibility with Clang/LLD - Support for TX2 system PMUS for profiling the L3 cache and DMC - Reflect read-only permissions in the linear map by default - Ensure MMIO reads are ordered with subsequent calls to Xdelay() - Initial support for memory hotplug - Tweak the threshold when we invalidate the TLB by-ASID, so that mremap() performance is improved for ranges spanning multiple PMDs. - Minor refactoring and cleanups" * tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (125 commits) arm64: kaslr: print PHYS_OFFSET in dump_kernel_offset() arm64: sysreg: Use _BITUL() when defining register bits arm64: cpufeature: Rework ptr auth hwcaps using multi_entry_cap_matches arm64: cpufeature: Reduce number of pointer auth CPU caps from 6 to 4 arm64: docs: document pointer authentication arm64: ptr auth: Move per-thread keys from thread_info to thread_struct arm64: enable pointer authentication arm64: add prctl control for resetting ptrauth keys arm64: perf: strip PAC when unwinding userspace arm64: expose user PAC bit positions via ptrace arm64: add basic pointer authentication support arm64/cpufeature: detect pointer authentication arm64: Don't trap host pointer auth use to EL2 arm64/kvm: hide ptrauth from guests arm64/kvm: consistently handle host HCR_EL2 flags arm64: add pointer authentication register bits arm64: add comments about EC exception levels arm64: perf: Treat EXCLUDE_EL* bit definitions as unsigned arm64: kpti: Whitelist Cortex-A CPUs that don't implement the CSV3 field arm64: enable per-task stack canaries ...
2018-12-25Merge tag 'drm-next-2018-12-14' of git://anongit.freedesktop.org/drm/drmLinus Torvalds2-12/+12
Pull drm updates from Dave Airlie: "Core: - shared fencing staging removal - drop transactional atomic helpers and move helpers to new location - DP/MST atomic cleanup - Leasing cleanups and drop EXPORT_SYMBOL - Convert drivers to atomic helpers and generic fbdev. - removed deprecated obj_ref/unref in favour of get/put - Improve dumb callback documentation - MODESET_LOCK_BEGIN/END helpers panels: - CDTech panels, Banana Pi Panel, DLC1010GIG, - Olimex LCD-O-LinuXino, Samsung S6D16D0, Truly NT35597 WQXGA, - Himax HX8357D, simulated RTSM AEMv8. - GPD Win2 panel - AUO G101EVN010 vgem: - render node support ttm: - move global init out of drivers - fix LRU handling for ghost objects - Support for simultaneous submissions to multiple engines scheduler: - timeout/fault handling changes to help GPU recovery - helpers for hw with preemption support i915: - Scaler/Watermark fixes - DP MST + powerwell fixes - PSR fixes - Break long get/put shmemfs pages - Icelake fixes - Icelake DSI video mode enablement - Engine workaround improvements amdgpu: - freesync support - GPU reset enabled on CI, VI, SOC15 dGPUs - ABM support in DC - KFD support for vega12/polaris12 - SDMA paging queue on vega - More amdkfd code sharing - DCC scanout on GFX9 - DC kerneldoc - Updated SMU firmware for GFX8 chips - XGMI PSP + hive reset support - GPU reset - DC trace support - Powerplay updates for newer Polaris - Cursor plane update fast path - kfd dma-buf support virtio-gpu: - add EDID support vmwgfx: - pageflip with damage support nouveau: - Initial Turing TU104/TU106 modesetting support msm: - a2xx gpu support for apq8060 and imx5 - a2xx gpummu support - mdp4 display support for apq8060 - DPU fixes and cleanups - enhanced profiling support - debug object naming interface - get_iova/page pinning decoupling tegra: - Tegra194 host1x, VIC and display support enabled - Audio over HDMI for Tegra186 and Tegra194 exynos: - DMA/IOMMU refactoring - plane alpha + blend mode support - Color format fixes for mixer driver rcar-du: - R8A7744 and R8A77470 support - R8A77965 LVDS support imx: - fbdev emulation fix - multi-tiled scalling fixes - SPDX identifiers rockchip - dw_hdmi support - dw-mipi-dsi + dual dsi support - mailbox read size fix qxl: - fix cursor pinning vc4: - YUV support (scaling + cursor) v3d: - enable TFU (Texture Formatting Unit) mali-dp: - add support for linear tiled formats sun4i: - Display Engine 3 support - H6 DE3 mixer 0 support - H6 display engine support - dw-hdmi support - H6 HDMI phy support - implicit fence waiting - BGRX8888 support meson: - Overlay plane support - implicit fence waiting - HDMI 1.4 4k modes bridge: - i2c fixes for sii902x" * tag 'drm-next-2018-12-14' of git://anongit.freedesktop.org/drm/drm: (1403 commits) drm/amd/display: Add fast path for cursor plane updates drm/amdgpu: Enable GPU recovery by default for CI drm/amd/display: Fix duplicating scaling/underscan connector state drm/amd/display: Fix unintialized max_bpc state values Revert "drm/amd/display: Set RMX_ASPECT as default" drm/amdgpu: Fix stub function name drm/msm/dpu: Fix clock issue after bind failure drm/msm/dpu: Clean up dpu_media_info.h static inline functions drm/msm/dpu: Further cleanups for static inline functions drm/msm/dpu: Cleanup the debugfs functions drm/msm/dpu: Remove dpu_irq and unused functions drm/msm: Make irq_postinstall optional drm/msm/dpu: Cleanup callers of dpu_hw_blk_init drm/msm/dpu: Remove unused functions drm/msm/dpu: Remove dpu_crtc_is_enabled() drm/msm/dpu: Remove dpu_crtc_get_mixer_height drm/msm/dpu: Remove dpu_dbg drm/msm: dpu: Remove crtc_lock drm/msm: dpu: Remove vblank_requested flag from dpu_crtc drm/msm: dpu: Separate crtc assignment from vblank enable ...
2018-12-22mm, page_alloc: fix has_unmovable_pages for HugePagesOscar Salvador1-2/+5
While playing with gigantic hugepages and memory_hotplug, I triggered the following #PF when "cat memoryX/removable": BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 #PF error: [normal kernel read fault] PGD 0 P4D 0 Oops: 0000 [#1] SMP PTI CPU: 1 PID: 1481 Comm: cat Tainted: G E 4.20.0-rc6-mm1-1-default+ #18 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.0.0-prebuilt.qemu-project.org 04/01/2014 RIP: 0010:has_unmovable_pages+0x154/0x210 Call Trace: is_mem_section_removable+0x7d/0x100 removable_show+0x90/0xb0 dev_attr_show+0x1c/0x50 sysfs_kf_seq_show+0xca/0x1b0 seq_read+0x133/0x380 __vfs_read+0x26/0x180 vfs_read+0x89/0x140 ksys_read+0x42/0x90 do_syscall_64+0x5b/0x180 entry_SYSCALL_64_after_hwframe+0x44/0xa9 The reason is we do not pass the Head to page_hstate(), and so, the call to compound_order() in page_hstate() returns 0, so we end up checking all hstates's size to match PAGE_SIZE. Obviously, we do not find any hstate matching that size, and we return NULL. Then, we dereference that NULL pointer in hugepage_migration_supported() and we got the #PF from above. Fix that by getting the head page before calling page_hstate(). Also, since gigantic pages span several pageblocks, re-adjust the logic for skipping pages. While are it, we can also get rid of the round_up(). [osalvador@suse.de: remove round_up(), adjust skip pages logic per Michal] Link: http://lkml.kernel.org/r/20181221062809.31771-1-osalvador@suse.de Link: http://lkml.kernel.org/r/20181217225113.17864-1-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Pavel Tatashin <pavel.tatashin@microsoft.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-22mm: thp: fix flags for pmd migration when splitPeter Xu1-9/+11
When splitting a huge migrating PMD, we'll transfer all the existing PMD bits and apply them again onto the small PTEs. However we are fetching the bits unconditionally via pmd_soft_dirty(), pmd_write() or pmd_yound() while actually they don't make sense at all when it's a migration entry. Fix them up. Since at it, drop the ifdef together as not needed. Note that if my understanding is correct about the problem then if without the patch there is chance to lose some of the dirty bits in the migrating pmd pages (on x86_64 we're fetching bit 11 which is part of swap offset instead of bit 2) and it could potentially corrupt the memory of an userspace program which depends on the dirty bit. Link: http://lkml.kernel.org/r/20181213051510.20306-1-peterx@redhat.com Signed-off-by: Peter Xu <peterx@redhat.com> Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Reviewed-by: William Kucharski <william.kucharski@oracle.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Dave Jiang <dave.jiang@intel.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Souptick Joarder <jrdr.linux@gmail.com> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Cc: <stable@vger.kernel.org> [4.14+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-22mm, memory_hotplug: initialize struct pages for the full memory sectionMikhail Zaslonko1-0/+12
If memory end is not aligned with the sparse memory section boundary, the mapping of such a section is only partly initialized. This may lead to VM_BUG_ON due to uninitialized struct page access from is_mem_section_removable() or test_pages_in_a_zone() function triggered by memory_hotplug sysfs handlers: Here are the the panic examples: CONFIG_DEBUG_VM=y CONFIG_DEBUG_VM_PGFLAGS=y kernel parameter mem=2050M -------------------------- page:000003d082008000 is uninitialized and poisoned page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p)) Call Trace: ( test_pages_in_a_zone+0xde/0x160) show_valid_zones+0x5c/0x190 dev_attr_show+0x34/0x70 sysfs_kf_seq_show+0xc8/0x148 seq_read+0x204/0x480 __vfs_read+0x32/0x178 vfs_read+0x82/0x138 ksys_read+0x5a/0xb0 system_call+0xdc/0x2d8 Last Breaking-Event-Address: test_pages_in_a_zone+0xde/0x160 Kernel panic - not syncing: Fatal exception: panic_on_oops kernel parameter mem=3075M -------------------------- page:000003d08300c000 is uninitialized and poisoned page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p)) Call Trace: ( is_mem_section_removable+0xb4/0x190) show_mem_removable+0x9a/0xd8 dev_attr_show+0x34/0x70 sysfs_kf_seq_show+0xc8/0x148 seq_read+0x204/0x480 __vfs_read+0x32/0x178 vfs_read+0x82/0x138 ksys_read+0x5a/0xb0 system_call+0xdc/0x2d8 Last Breaking-Event-Address: is_mem_section_removable+0xb4/0x190 Kernel panic - not syncing: Fatal exception: panic_on_oops Fix the problem by initializing the last memory section of each zone in memmap_init_zone() till the very end, even if it goes beyond the zone end. Michal said: : This has alwways been problem AFAIU. It just went unnoticed because we : have zeroed memmaps during allocation before f7f99100d8d9 ("mm: stop : zeroing memory during allocation in vmemmap") and so the above test : would simply skip these ranges as belonging to zone 0 or provided a : garbage. : : So I guess we do care for post f7f99100d8d9 kernels mostly and : therefore Fixes: f7f99100d8d9 ("mm: stop zeroing memory during : allocation in vmemmap") Link: http://lkml.kernel.org/r/20181212172712.34019-2-zaslonko@linux.ibm.com Fixes: f7f99100d8d9 ("mm: stop zeroing memory during allocation in vmemmap") Signed-off-by: Mikhail Zaslonko <zaslonko@linux.ibm.com> Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Suggested-by: Michal Hocko <mhocko@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Reported-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com> Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com> Cc: Pasha Tatashin <Pavel.Tatashin@microsoft.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-15hugetlbfs: call VM_BUG_ON_PAGE earlier in free_huge_page()Yongkai Wu1-2/+3
A stack trace was triggered by VM_BUG_ON_PAGE(page_mapcount(page), page) in free_huge_page(). Unfortunately, the page->mapping field was set to NULL before this test. This made it more difficult to determine the root cause of the problem. Move the VM_BUG_ON_PAGE tests earlier in the function so that if they do trigger more information is present in the page struct. Link: http://lkml.kernel.org/r/1543491843-23438-1-git-send-email-nic_w@163.com Signed-off-by: Yongkai Wu <nic_w@163.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: William Kucharski <william.kucharski@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-15memblock: annotate memblock_is_reserved() with __init_memblockYueyi Li1-1/+1
Found warning: WARNING: EXPORT symbol "gsi_write_channel_scratch" [vmlinux] version generation failed, symbol will not be versioned. WARNING: vmlinux.o(.text+0x1e0a0): Section mismatch in reference from the function valid_phys_addr_range() to the function .init.text:memblock_is_reserved() The function valid_phys_addr_range() references the function __init memblock_is_reserved(). This is often because valid_phys_addr_range lacks a __init annotation or the annotation of memblock_is_reserved is wrong. Use __init_memblock instead of __init. Link: http://lkml.kernel.org/r/BLUPR13MB02893411BF12EACB61888E80DFAE0@BLUPR13MB0289.namprd13.prod.outlook.com Signed-off-by: Yueyi Li <liyueyi@live.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: David Hildenbrand <david@redhat.com> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-15mm/sparse: add common helper to mark all memblocks presentLogan Gunthorpe1-0/+16
Presently the arches arm64, arm and sh have a function which loops through each memblock and calls memory present. riscv will require a similar function. Introduce a common memblocks_present() function that can be used by all the arches. Subsequent patches will cleanup the arches that make use of this. Link: http://lkml.kernel.org/r/20181107205433.3875-3-logang@deltatee.com Signed-off-by: Logan Gunthorpe <logang@deltatee.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-14Merge tag 'xarray-4.20-rc7' of git://git.infradead.org/users/willy/linux-daxLinus Torvalds1-3/+1
Pull XArray fixes from Matthew Wilcox: "Two bugfixes, each with test-suite updates, two improvements to the test-suite without associated bugs, and one patch adding a missing API" * tag 'xarray-4.20-rc7' of git://git.infradead.org/users/willy/linux-dax: XArray: Fix xa_alloc when id exceeds max XArray tests: Check iterating over multiorder entries XArray tests: Handle larger indices more elegantly XArray: Add xa_cmpxchg_irq and xa_cmpxchg_bh radix tree: Don't return retry entries from lookup
2018-12-10mm: mmap: Allow for "high" userspace addressesSteve Capper1-7/+18
This patch adds support for "high" userspace addresses that are optionally supported on the system and have to be requested via a hint mechanism ("high" addr parameter to mmap). Architectures such as powerpc and x86 achieve this by making changes to their architectural versions of arch_get_unmapped_* functions. However, on arm64 we use the generic versions of these functions. Rather than duplicate the generic arch_get_unmapped_* implementations for arm64, this patch instead introduces two architectural helper macros and applies them to arch_get_unmapped_*: arch_get_mmap_end(addr) - get mmap upper limit depending on addr hint arch_get_mmap_base(addr, base) - get mmap_base depending on addr hint If these macros are not defined in architectural code then they default to (TASK_SIZE) and (base) so should not introduce any behavioural changes to architectures that do not define them. Signed-off-by: Steve Capper <steve.capper@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-12-09Merge tag 'dax-fixes-4.20-rc6' of ↵Linus Torvalds1-2/+4
git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm Pull dax fixes from Dan Williams: "The last of the known regression fixes and fallout from the Xarray conversion of the filesystem-dax implementation. On the path to debugging why the dax memory-failure injection test started failing after the Xarray conversion a couple more fixes for the dax_lock_mapping_entry(), now called dax_lock_page(), surfaced. Those plus the bug that started the hunt are now addressed. These patches have appeared in a -next release with no issues reported. Note the touches to mm/memory-failure.c are just the conversion to the new function signature for dax_lock_page(). Summary: - Fix the Xarray conversion of fsdax to properly handle dax_lock_mapping_entry() in the presense of pmd entries - Fix inode destruction racing a new lock request" * tag 'dax-fixes-4.20-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm: dax: Fix unlock mismatch with updated API dax: Don't access a freed inode dax: Check page->mapping isn't NULL
2018-12-08Revert "mm, thp: consolidate THP gfp handling into ↵David Rientjes3-18/+43
alloc_hugepage_direct_gfpmask" This reverts commit 89c83fb539f95491be80cdd5158e6f0ce329e317. This should have been done as part of 2f0799a0ffc0 ("mm, thp: restore node-local hugepage allocations"). The movement of the thp allocation policy from alloc_pages_vma() to alloc_hugepage_direct_gfpmask() was intended to only set __GFP_THISNODE for mempolicies that are not MPOL_BIND whereas the revert could set this regardless of mempolicy. While the check for MPOL_BIND between alloc_hugepage_direct_gfpmask() and alloc_pages_vma() was racy, that has since been removed since the revert. What is left is the possibility to use __GFP_THISNODE in policy_node() when it is unexpected because the special handling for hugepages in alloc_pages_vma() was removed as part of the consolidation. Secondly, prior to 89c83fb539f9, alloc_pages_vma() implemented a somewhat different policy for hugepage allocations, which were allocated through alloc_hugepage_vma(). For hugepage allocations, if the allocating process's node is in the set of allowed nodes, allocate with __GFP_THISNODE for that node (for MPOL_PREFERRED, use that node with __GFP_THISNODE instead). This was changed for shmem_alloc_hugepage() to allow fallback to other nodes in 89c83fb539f9 as it did for new_page() in mm/mempolicy.c which is functionally different behavior and removes the requirement to only allocate hugepages locally. So this commit does a full revert of 89c83fb539f9 instead of the partial revert that was done in 2f0799a0ffc0. The result is the same thp allocation policy for 4.20 that was in 4.19. Fixes: 89c83fb539f9 ("mm, thp: consolidate THP gfp handling into alloc_hugepage_direct_gfpmask") Fixes: 2f0799a0ffc0 ("mm, thp: restore node-local hugepage allocations") Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-06XArray: Add xa_cmpxchg_irq and xa_cmpxchg_bhMatthew Wilcox1-3/+1
These convenience wrappers match the other _irq and _bh wrappers we already have. It turns out I'd already open-coded xa_cmpxchg_irq() in the shmem code, so convert that. Signed-off-by: Matthew Wilcox <willy@infradead.org>
2018-12-06mm, thp: restore node-local hugepage allocationsDavid Rientjes2-27/+17
This is a full revert of ac5b2c18911f ("mm: thp: relax __GFP_THISNODE for MADV_HUGEPAGE mappings") and a partial revert of 89c83fb539f9 ("mm, thp: consolidate THP gfp handling into alloc_hugepage_direct_gfpmask"). By not setting __GFP_THISNODE, applications can allocate remote hugepages when the local node is fragmented or low on memory when either the thp defrag setting is "always" or the vma has been madvised with MADV_HUGEPAGE. Remote access to hugepages often has much higher latency than local pages of the native page size. On Haswell, ac5b2c18911f was shown to have a 13.9% access regression after this commit for binaries that remap their text segment to be backed by transparent hugepages. The intent of ac5b2c18911f is to address an issue where a local node is low on memory or fragmented such that a hugepage cannot be allocated. In every scenario where this was described as a fix, there is abundant and unfragmented remote memory available to allocate from, even with a greater access latency. If remote memory is also low or fragmented, not setting __GFP_THISNODE was also measured on Haswell to have a 40% regression in allocation latency. Restore __GFP_THISNODE for thp allocations. Fixes: ac5b2c18911f ("mm: thp: relax __GFP_THISNODE for MADV_HUGEPAGE mappings") Fixes: 89c83fb539f9 ("mm, thp: consolidate THP gfp handling into alloc_hugepage_direct_gfpmask") Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-05dax: Fix unlock mismatch with updated APIMatthew Wilcox1-2/+4
Internal to dax_unlock_mapping_entry(), dax_unlock_entry() is used to store a replacement entry in the Xarray at the given xas-index with the DAX_LOCKED bit clear. When called, dax_unlock_entry() expects the unlocked value of the entry relative to the current Xarray state to be specified. In most contexts dax_unlock_entry() is operating in the same scope as the matched dax_lock_entry(). However, in the dax_unlock_mapping_entry() case the implementation needs to recall the original entry. In the case where the original entry is a 'pmd' entry it is possible that the pfn performed to do the lookup is misaligned to the value retrieved in the Xarray. Change the api to return the unlock cookie from dax_lock_page() and pass it to dax_unlock_page(). This fixes a bug where dax_unlock_page() was assuming that the page was PMD-aligned if the entry was a PMD entry with signatures like: WARNING: CPU: 38 PID: 1396 at fs/dax.c:340 dax_insert_entry+0x2b2/0x2d0 RIP: 0010:dax_insert_entry+0x2b2/0x2d0 [..] Call Trace: dax_iomap_pte_fault.isra.41+0x791/0xde0 ext4_dax_huge_fault+0x16f/0x1f0 ? up_read+0x1c/0xa0 __do_fault+0x1f/0x160 __handle_mm_fault+0x1033/0x1490 handle_mm_fault+0x18b/0x3d0 Link: https://lkml.kernel.org/r/20181130154902.GL10377@bombadil.infradead.org Fixes: 9f32d221301c ("dax: Convert dax_lock_mapping_entry to XArray") Reported-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Matthew Wilcox <willy@infradead.org> Tested-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2018-12-04Merge branch 'for-mingo' of ↵Ingo Molnar5-10/+9
git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu Pull RCU changes from Paul E. McKenney: - Convert RCU's BUG_ON() and similar calls to WARN_ON() and similar. - Replace calls of RCU-bh and RCU-sched update-side functions to their vanilla RCU counterparts. This series is a step towards complete removal of the RCU-bh and RCU-sched update-side functions. ( Note that some of these conversions are going upstream via their respective maintainers. ) - Documentation updates, including a number of flavor-consolidation updates from Joel Fernandes. - Miscellaneous fixes. - Automate generation of the initrd filesystem used for rcutorture testing. - Convert spin_is_locked() assertions to instead use lockdep. ( Note that some of these conversions are going upstream via their respective maintainers. ) - SRCU updates, especially including a fix from Dennis Krein for a bag-on-head-class bug. - RCU torture-test updates. Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-12-01Merge branches 'bug.2018.11.12a', 'consolidate.2018.12.01a', ↵Paul E. McKenney5-10/+9
'doc.2018.11.12a', 'fixes.2018.11.12a', 'initrd.2018.11.08b', 'sil.2018.11.12a' and 'srcu.2018.11.27a' into HEAD bug.2018.11.12a: Get rid of BUG_ON() and friends consolidate.2018.12.01a: Continued RCU flavor-consolidation cleanup doc.2018.11.12a: Documentation updates fixes.2018.11.12a: Miscellaneous fixes initrd.2018.11.08b: Automate creation of rcutorture initrd sil.2018.11.12a: Remove more spin_unlock_wait() calls
2018-12-01mm/khugepaged: fix the xas_create_range() error pathHugh Dickins1-11/+14
collapse_shmem()'s xas_nomem() is very unlikely to fail, but it is rightly given a failure path, so move the whole xas_create_range() block up before __SetPageLocked(new_page): so that it does not need to remember to unlock_page(new_page). Add the missing mem_cgroup_cancel_charge(), and set (currently unused) result to SCAN_FAIL rather than SCAN_SUCCEED. Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261531200.2275@eggly.anvils Fixes: 77da9389b9d5 ("mm: Convert collapse_shmem to XArray") Signed-off-by: Hugh Dickins <hughd@kernel.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-01mm/khugepaged: collapse_shmem() do not crash on CompoundHugh Dickins1-1/+9
collapse_shmem()'s VM_BUG_ON_PAGE(PageTransCompound) was unsafe: before it holds page lock of the first page, racing truncation then extension might conceivably have inserted a hugepage there already. Fail with the SCAN_PAGE_COMPOUND result, instead of crashing (CONFIG_DEBUG_VM=y) or otherwise mishandling the unexpected hugepage - though later we might code up a more constructive way of handling it, with SCAN_SUCCESS. Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261529310.2275@eggly.anvils Fixes: f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages") Signed-off-by: Hugh Dickins <hughd@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Matthew Wilcox <willy@infradead.org> Cc: <stable@vger.kernel.org> [4.8+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-01mm/khugepaged: collapse_shmem() without freezing new_pageHugh Dickins1-12/+7
khugepaged's collapse_shmem() does almost all of its work, to assemble the huge new_page from 512 scattered old pages, with the new_page's refcount frozen to 0 (and refcounts of all old pages so far also frozen to 0). Including shmem_getpage() to read in any which were out on swap, memory reclaim if necessary to allocate their intermediate pages, and copying over all the data from old to new. Imagine the frozen refcount as a spinlock held, but without any lock debugging to highlight the abuse: it's not good, and under serious load heads into lockups - speculative getters of the page are not expecting to spin while khugepaged is rescheduled. One can get a little further under load by hacking around elsewhere; but fortunately, freezing the new_page turns out to have been entirely unnecessary, with no hacks needed elsewhere. The huge new_page lock is already held throughout, and guards all its subpages as they are brought one by one into the page cache tree; and anything reading the data in that page, without the lock, before it has been marked PageUptodate, would already be in the wrong. So simply eliminate the freezing of the new_page. Each of the old pages remains frozen with refcount 0 after it has been replaced by a new_page subpage in the page cache tree, until they are all unfrozen on success or failure: just as before. They could be unfrozen sooner, but cause no problem once no longer visible to find_get_entry(), filemap_map_pages() and other speculative lookups. Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261527570.2275@eggly.anvils Fixes: f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages") Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Matthew Wilcox <willy@infradead.org> Cc: <stable@vger.kernel.org> [4.8+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-01mm/khugepaged: minor reorderings in collapse_shmem()Hugh Dickins1-40/+32
Several cleanups in collapse_shmem(): most of which probably do not really matter, beyond doing things in a more familiar and reassuring order. Simplify the failure gotos in the main loop, and on success update stats while interrupts still disabled from the last iteration. Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261526400.2275@eggly.anvils Fixes: f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages") Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Matthew Wilcox <willy@infradead.org> Cc: <stable@vger.kernel.org> [4.8+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-01mm/khugepaged: collapse_shmem() remember to clear holesHugh Dickins1-0/+10
Huge tmpfs testing reminds us that there is no __GFP_ZERO in the gfp flags khugepaged uses to allocate a huge page - in all common cases it would just be a waste of effort - so collapse_shmem() must remember to clear out any holes that it instantiates. The obvious place to do so, where they are put into the page cache tree, is not a good choice: because interrupts are disabled there. Leave it until further down, once success is assured, where the other pages are copied (before setting PageUptodate). Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261525080.2275@eggly.anvils Fixes: f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages") Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Matthew Wilcox <willy@infradead.org> Cc: <stable@vger.kernel.org> [4.8+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-01mm/khugepaged: fix crashes due to misaccounted holesHugh Dickins2-2/+9
Huge tmpfs testing on a shortish file mapped into a pmd-rounded extent hit shmem_evict_inode()'s WARN_ON(inode->i_blocks) followed by clear_inode()'s BUG_ON(inode->i_data.nrpages) when the file was later closed and unlinked. khugepaged's collapse_shmem() was forgetting to update mapping->nrpages on the rollback path, after it had added but then needs to undo some holes. There is indeed an irritating asymmetry between shmem_charge(), whose callers want it to increment nrpages after successfully accounting blocks, and shmem_uncharge(), when __delete_from_page_cache() already decremented nrpages itself: oh well, just add a comment on that to them both. And shmem_recalc_inode() is supposed to be called when the accounting is expected to be in balance (so it can deduce from imbalance that reclaim discarded some pages): so change shmem_charge() to update nrpages earlier (though it's rare for the difference to matter at all). Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261523450.2275@eggly.anvils Fixes: 800d8c63b2e98 ("shmem: add huge pages support") Fixes: f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages") Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Matthew Wilcox <willy@infradead.org> Cc: <stable@vger.kernel.org> [4.8+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-01mm/khugepaged: collapse_shmem() stop if punched or truncatedHugh Dickins1-0/+11
Huge tmpfs testing showed that although collapse_shmem() recognizes a concurrently truncated or hole-punched page correctly, its handling of holes was liable to refill an emptied extent. Add check to stop that. Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261522040.2275@eggly.anvils Fixes: f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages") Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: Matthew Wilcox <willy@infradead.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: <stable@vger.kernel.org> [4.8+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-01mm/huge_memory: fix lockdep complaint on 32-bit i_size_read()Hugh Dickins1-6/+13
Huge tmpfs testing, on 32-bit kernel with lockdep enabled, showed that __split_huge_page() was using i_size_read() while holding the irq-safe lru_lock and page tree lock, but the 32-bit i_size_read() uses an irq-unsafe seqlock which should not be nested inside them. Instead, read the i_size earlier in split_huge_page_to_list(), and pass the end offset down to __split_huge_page(): all while holding head page lock, which is enough to prevent truncation of that extent before the page tree lock has been taken. Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261520070.2275@eggly.anvils Fixes: baa355fd33142 ("thp: file pages support for split_huge_page()") Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Matthew Wilcox <willy@infradead.org> Cc: <stable@vger.kernel.org> [4.8+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-01mm/huge_memory: splitting set mapping+index before unfreezeHugh Dickins1-6/+6
Huge tmpfs stress testing has occasionally hit shmem_undo_range()'s VM_BUG_ON_PAGE(page_to_pgoff(page) != index, page). Move the setting of mapping and index up before the page_ref_unfreeze() in __split_huge_page_tail() to fix this: so that a page cache lookup cannot get a reference while the tail's mapping and index are unstable. In fact, might as well move them up before the smp_wmb(): I don't see an actual need for that, but if I'm missing something, this way round is safer than the other, and no less efficient. You might argue that VM_BUG_ON_PAGE(page_to_pgoff(page) != index, page) is misplaced, and should be left until after the trylock_page(); but left as is has not crashed since, and gives more stringent assurance. Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261516380.2275@eggly.anvils Fixes: e9b61f19858a5 ("thp: reintroduce split_huge_page()") Requires: 605ca5ede764 ("mm/huge_memory.c: reorder operations in __split_huge_page_tail()") Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: <stable@vger.kernel.org> [4.8+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-01mm/huge_memory: rename freeze_page() to unmap_page()Hugh Dickins2-16/+9
The term "freeze" is used in several ways in the kernel, and in mm it has the particular meaning of forcing page refcount temporarily to 0. freeze_page() is just too confusing a name for a function that unmaps a page: rename it unmap_page(), and rename unfreeze_page() remap_page(). Went to change the mention of freeze_page() added later in mm/rmap.c, but found it to be incorrect: ordinary page reclaim reaches there too; but the substance of the comment still seems correct, so edit it down. Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261514080.2275@eggly.anvils Fixes: e9b61f19858a5 ("thp: reintroduce split_huge_page()") Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Matthew Wilcox <willy@infradead.org> Cc: <stable@vger.kernel.org> [4.8+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-01userfaultfd: shmem: UFFDIO_COPY: set the page dirty if VM_WRITE is not setAndrea Arcangeli1-0/+11
Set the page dirty if VM_WRITE is not set because in such case the pte won't be marked dirty and the page would be reclaimed without writepage (i.e. swapout in the shmem case). This was found by source review. Most apps (certainly including QEMU) only use UFFDIO_COPY on PROT_READ|PROT_WRITE mappings or the app can't modify the memory in the first place. This is for correctness and it could help the non cooperative use case to avoid unexpected data loss. Link: http://lkml.kernel.org/r/20181126173452.26955-6-aarcange@redhat.com Reviewed-by: Hugh Dickins <hughd@google.com> Cc: stable@vger.kernel.org Fixes: 4c27fe4c4c84 ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support") Reported-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-01userfaultfd: shmem: add i_size checksAndrea Arcangeli2-4/+40
With MAP_SHARED: recheck the i_size after taking the PT lock, to serialize against truncate with the PT lock. Delete the page from the pagecache if the i_size_read check fails. With MAP_PRIVATE: check the i_size after the PT lock before mapping anonymous memory or zeropages into the MAP_PRIVATE shmem mapping. A mostly irrelevant cleanup: like we do the delete_from_page_cache() pagecache removal after dropping the PT lock, the PT lock is a spinlock so drop it before the sleepable page lock. Link: http://lkml.kernel.org/r/20181126173452.26955-5-aarcange@redhat.com Fixes: 4c27fe4c4c84 ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support") Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reviewed-by: Mike Rapoport <rppt@linux.ibm.com> Reviewed-by: Hugh Dickins <hughd@google.com> Reported-by: Jann Horn <jannh@google.com> Cc: <stable@vger.kernel.org> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Peter Xu <peterx@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-01userfaultfd: shmem/hugetlbfs: only allow to register VM_MAYWRITE vmasAndrea Arcangeli1-9/+6
After the VMA to register the uffd onto is found, check that it has VM_MAYWRITE set before allowing registration. This way we inherit all common code checks before allowing to fill file holes in shmem and hugetlbfs with UFFDIO_COPY. The userfaultfd memory model is not applicable for readonly files unless it's a MAP_PRIVATE. Link: http://lkml.kernel.org/r/20181126173452.26955-4-aarcange@redhat.com Fixes: ff62a3421044 ("hugetlb: implement memfd sealing") Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reviewed-by: Mike Rapoport <rppt@linux.ibm.com> Reviewed-by: Hugh Dickins <hughd@google.com> Reported-by: Jann Horn <jannh@google.com> Fixes: 4c27fe4c4c84 ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support") Cc: <stable@vger.kernel.org> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Peter Xu <peterx@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-01userfaultfd: shmem: allocate anonymous memory for MAP_PRIVATE shmemAndrea Arcangeli1-2/+13
Userfaultfd did not create private memory when UFFDIO_COPY was invoked on a MAP_PRIVATE shmem mapping. Instead it wrote to the shmem file, even when that had not been opened for writing. Though, fortunately, that could only happen where there was a hole in the file. Fix the shmem-backed implementation of UFFDIO_COPY to create private memory for MAP_PRIVATE mappings. The hugetlbfs-backed implementation was already correct. This change is visible to userland, if userfaultfd has been used in unintended ways: so it introduces a small risk of incompatibility, but is necessary in order to respect file permissions. An app that uses UFFDIO_COPY for anything like postcopy live migration won't notice the difference, and in fact it'll run faster because there will be no copy-on-write and memory waste in the tmpfs pagecache anymore. Userfaults on MAP_PRIVATE shmem keep triggering only on file holes like before. The real zeropage can also be built on a MAP_PRIVATE shmem mapping through UFFDIO_ZEROPAGE and that's safe because the zeropage pte is never dirty, in turn even an mprotect upgrading the vma permission from PROT_READ to PROT_READ|PROT_WRITE won't make the zeropage pte writable. Link: http://lkml.kernel.org/r/20181126173452.26955-3-aarcange@redhat.com Fixes: 4c27fe4c4c84 ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support") Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reported-by: Mike Rapoport <rppt@linux.ibm.com> Reviewed-by: Hugh Dickins <hughd@google.com> Cc: <stable@vger.kernel.org> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Peter Xu <peterx@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-01userfaultfd: use ENOENT instead of EFAULT if the atomic copy user failsAndrea Arcangeli3-5/+5
Patch series "userfaultfd shmem updates". Jann found two bugs in the userfaultfd shmem MAP_SHARED backend: the lack of the VM_MAYWRITE check and the lack of i_size checks. Then looking into the above we also fixed the MAP_PRIVATE case. Hugh by source review also found a data loss source if UFFDIO_COPY is used on shmem MAP_SHARED PROT_READ mappings (the production usages incidentally run with PROT_READ|PROT_WRITE, so the data loss couldn't happen in those production usages like with QEMU). The whole patchset is marked for stable. We verified QEMU postcopy live migration with guest running on shmem MAP_PRIVATE run as well as before after the fix of shmem MAP_PRIVATE. Regardless if it's shmem or hugetlbfs or MAP_PRIVATE or MAP_SHARED, QEMU unconditionally invokes a punch hole if the guest mapping is filebacked and a MADV_DONTNEED too (needed to get rid of the MAP_PRIVATE COWs and for the anon backend). This patch (of 5): We internally used EFAULT to communicate with the caller, switch to ENOENT, so EFAULT can be used as a non internal retval. Link: http://lkml.kernel.org/r/20181126173452.26955-2-aarcange@redhat.com Fixes: 4c27fe4c4c84 ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support") Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reviewed-by: Mike Rapoport <rppt@linux.ibm.com> Reviewed-by: Hugh Dickins <hughd@google.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Jann Horn <jannh@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Cc: <stable@vger.kernel.org> Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-01mm/page_alloc.c: fix calculation of pgdat->nr_zonesWei Yang1-1/+3
init_currently_empty_zone() will adjust pgdat->nr_zones and set it to 'zone_idx(zone) + 1' unconditionally. This is correct in the normal case, while not exact in hot-plug situation. This function is used in two places: * free_area_init_core() * move_pfn_range_to_zone() In the first case, we are sure zone index increase monotonically. While in the second one, this is under users control. One way to reproduce this is: ---------------------------- 1. create a virtual machine with empty node1 -m 4G,slots=32,maxmem=32G \ -smp 4,maxcpus=8 \ -numa node,nodeid=0,mem=4G,cpus=0-3 \ -numa node,nodeid=1,mem=0G,cpus=4-7 2. hot-add cpu 3-7 cpu-add [3-7] 2. hot-add memory to nod1 object_add memory-backend-ram,id=ram0,size=1G device_add pc-dimm,id=dimm0,memdev=ram0,node=1 3. online memory with following order echo online_movable > memory47/state echo online > memory40/state After this, node1 will have its nr_zones equals to (ZONE_NORMAL + 1) instead of (ZONE_MOVABLE + 1). Michal said: "Having an incorrect nr_zones might result in all sorts of problems which would be quite hard to debug (e.g. reclaim not considering the movable zone). I do not expect many users would suffer from this it but still this is trivial and obviously right thing to do so backporting to the stable tree shouldn't be harmful (last famous words)" Link: http://lkml.kernel.org/r/20181117022022.9956-1-richard.weiyang@gmail.com Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online") Signed-off-by: Wei Yang <richard.weiyang@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Dave Hansen <dave.hansen@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-01mm: use swp_offset as key in shmem_replace_page()Yu Zhao1-2/+4
We changed the key of swap cache tree from swp_entry_t.val to swp_offset. We need to do so in shmem_replace_page() as well. Hugh said: "shmem_replace_page() has been wrong since the day I wrote it: good enough to work on swap "type" 0, which is all most people ever use (especially those few who need shmem_replace_page() at all), but broken once there are any non-0 swp_type bits set in the higher order bits" Link: http://lkml.kernel.org/r/20181121215442.138545-1-yuzhao@google.com Fixes: f6ab1f7f6b2d ("mm, swap: use offset of swap entry as key of swap cache") Signed-off-by: Yu Zhao <yuzhao@google.com> Reviewed-by: Matthew Wilcox <willy@infradead.org> Acked-by: Hugh Dickins <hughd@google.com> Cc: <stable@vger.kernel.org> [4.9+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-01mm: cleancache: fix corruption on missed inode invalidationPavel Tikhomirov1-2/+6
If all pages are deleted from the mapping by memory reclaim and also moved to the cleancache: __delete_from_page_cache (no shadow case) unaccount_page_cache_page cleancache_put_page page_cache_delete mapping->nrpages -= nr (nrpages becomes 0) We don't clean the cleancache for an inode after final file truncation (removal). truncate_inode_pages_final check (nrpages || nrexceptional) is false no truncate_inode_pages no cleancache_invalidate_inode(mapping) These way when reading the new file created with same inode we may get these trash leftover pages from cleancache and see wrong data instead of the contents of the new file. Fix it by always doing truncate_inode_pages which is already ready for nrpages == 0 && nrexceptional == 0 case and just invalidates inode. [akpm@linux-foundation.org: add comment, per Jan] Link: http://lkml.kernel.org/r/20181112095734.17979-1-ptikhomirov@virtuozzo.com Fixes: commit 91b0abe36a7b ("mm + fs: store shadow entries in page cache") Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com> Reviewed-by: Vasily Averin <vvs@virtuozzo.com> Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>