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2021-03-09dm bufio: subtract the number of initial sectors in dm_bufio_get_device_sizeMikulas Patocka1-0/+4
commit a14e5ec66a7a66e57b24e2469f9212a78460207e upstream. dm_bufio_get_device_size returns the device size in blocks. Before returning the value, we must subtract the nubmer of starting sectors. The number of starting sectors may not be divisible by block size. Note that currently, no target is using dm_bufio_set_sector_offset and dm_bufio_get_device_size simultaneously, so this change has no effect. However, an upcoming dm-verity-fec fix needs this change. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Milan Broz <gmazyland@gmail.com> Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-19dm integrity: fix flush with external metadata deviceMikulas Patocka1-0/+6
[ Upstream commit 9b5948267adc9e689da609eb61cf7ed49cae5fa8 ] With external metadata device, flush requests are not passed down to the data device. Fix this by submitting the flush request in dm_integrity_flush_buffers. In order to not degrade performance, we overlap the data device flush with the metadata device flush. Reported-by: Lukas Straub <lukasstraub2@web.de> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-09-14dm bufio: introduce a global cache replacementMikulas Patocka1-7/+91
This commit introduces a global cache replacement (instead of per-client cleanup). If one bufio client uses the cache heavily and another client is not using it, we want to let the first client use most of the cache. The old algorithm would partition the cache equally betwen the clients and that is sub-optimal. For cache replacement, we use the clock algorithm because it doesn't require taking any lock when the buffer is accessed. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-09-13dm bufio: remove old-style buffer cleanupMikulas Patocka1-58/+3
Remove code that cleans up buffers if the cache size grows over the limit. The next commit will introduce a new global cleanup. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-09-13dm bufio: introduce a global queueMikulas Patocka1-3/+12
Rename param_spinlock to global_spinlock and introduce a global queue of all used buffers. The queue will be used in the following commits. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-09-13dm bufio: refactor adjust_total_allocatedMikulas Patocka1-3/+11
Refactor adjust_total_allocated() so that it takes a bool argument indicating if it should add or subtract the buffer size. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-09-13dm bufio: call adjust_total_allocated from __link_buffer and __unlink_bufferMikulas Patocka1-4/+4
Move the call to adjust_total_allocated() to __link_buffer() and __unlink_buffer() so that only used buffers are counted. Reserved buffers are not. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-08-15Revert "dm bufio: fix deadlock with loop device"Mikulas Patocka1-1/+3
Revert the commit bd293d071ffe65e645b4d8104f9d8fe15ea13862. The proper fix has been made available with commit d0a255e795ab ("loop: set PF_MEMALLOC_NOIO for the worker thread"). Note that the fix offered by commit bd293d071ffe doesn't really prevent the deadlock from occuring - if we look at the stacktrace reported by Junxiao Bi, we see that it hangs in bit_wait_io and not on the mutex - i.e. it has already successfully taken the mutex. Changing the mutex from mutex_lock to mutex_trylock won't help with deadlocks that happen afterwards. PID: 474 TASK: ffff8813e11f4600 CPU: 10 COMMAND: "kswapd0" #0 [ffff8813dedfb938] __schedule at ffffffff8173f405 #1 [ffff8813dedfb990] schedule at ffffffff8173fa27 #2 [ffff8813dedfb9b0] schedule_timeout at ffffffff81742fec #3 [ffff8813dedfba60] io_schedule_timeout at ffffffff8173f186 #4 [ffff8813dedfbaa0] bit_wait_io at ffffffff8174034f #5 [ffff8813dedfbac0] __wait_on_bit at ffffffff8173fec8 #6 [ffff8813dedfbb10] out_of_line_wait_on_bit at ffffffff8173ff81 #7 [ffff8813dedfbb90] __make_buffer_clean at ffffffffa038736f [dm_bufio] #8 [ffff8813dedfbbb0] __try_evict_buffer at ffffffffa0387bb8 [dm_bufio] #9 [ffff8813dedfbbd0] dm_bufio_shrink_scan at ffffffffa0387cc3 [dm_bufio] #10 [ffff8813dedfbc40] shrink_slab at ffffffff811a87ce #11 [ffff8813dedfbd30] shrink_zone at ffffffff811ad778 #12 [ffff8813dedfbdc0] kswapd at ffffffff811ae92f #13 [ffff8813dedfbec0] kthread at ffffffff810a8428 #14 [ffff8813dedfbf50] ret_from_fork at ffffffff81745242 Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Cc: stable@vger.kernel.org Fixes: bd293d071ffe ("dm bufio: fix deadlock with loop device") Depends-on: d0a255e795ab ("loop: set PF_MEMALLOC_NOIO for the worker thread") Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-07-12dm bufio: fix deadlock with loop deviceJunxiao Bi1-3/+1
When thin-volume is built on loop device, if available memory is low, the following deadlock can be triggered: One process P1 allocates memory with GFP_FS flag, direct alloc fails, memory reclaim invokes memory shrinker in dm_bufio, dm_bufio_shrink_scan() runs, mutex dm_bufio_client->lock is acquired, then P1 waits for dm_buffer IO to complete in __try_evict_buffer(). But this IO may never complete if issued to an underlying loop device that forwards it using direct-IO, which allocates memory using GFP_KERNEL (see: do_blockdev_direct_IO()). If allocation fails, memory reclaim will invoke memory shrinker in dm_bufio, dm_bufio_shrink_scan() will be invoked, and since the mutex is already held by P1 the loop thread will hang, and IO will never complete. Resulting in ABBA deadlock. Cc: stable@vger.kernel.org Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-04-29dm bufio: Simplify stack trace retrievalThomas Gleixner1-9/+6
Replace the indirection through struct stack_trace with an invocation of the storage array based interface. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: dm-devel@redhat.com Cc: Mike Snitzer <snitzer@redhat.com> Cc: Alasdair Kergon <agk@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Alexander Potapenko <glider@google.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: linux-mm@kvack.org Cc: David Rientjes <rientjes@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: kasan-dev@googlegroups.com Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Akinobu Mita <akinobu.mita@gmail.com> Cc: Christoph Hellwig <hch@lst.de> Cc: iommu@lists.linux-foundation.org Cc: Robin Murphy <robin.murphy@arm.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Johannes Thumshirn <jthumshirn@suse.de> Cc: David Sterba <dsterba@suse.com> Cc: Chris Mason <clm@fb.com> Cc: Josef Bacik <josef@toxicpanda.com> Cc: linux-btrfs@vger.kernel.org Cc: Daniel Vetter <daniel@ffwll.ch> Cc: intel-gfx@lists.freedesktop.org Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: dri-devel@lists.freedesktop.org Cc: David Airlie <airlied@linux.ie> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Tom Zanussi <tom.zanussi@linux.intel.com> Cc: Miroslav Benes <mbenes@suse.cz> Cc: linux-arch@vger.kernel.org Link: https://lkml.kernel.org/r/20190425094802.446326191@linutronix.de
2018-12-29Merge branch 'akpm' (patches from Andrew)Linus Torvalds1-1/+1
Merge misc updates from Andrew Morton: - large KASAN update to use arm's "software tag-based mode" - a few misc things - sh updates - ocfs2 updates - just about all of MM * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (167 commits) kernel/fork.c: mark 'stack_vm_area' with __maybe_unused memcg, oom: notify on oom killer invocation from the charge path mm, swap: fix swapoff with KSM pages include/linux/gfp.h: fix typo mm/hmm: fix memremap.h, move dev_page_fault_t callback to hmm hugetlbfs: Use i_mmap_rwsem to fix page fault/truncate race hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization memory_hotplug: add missing newlines to debugging output mm: remove __hugepage_set_anon_rmap() include/linux/vmstat.h: remove unused page state adjustment macro mm/page_alloc.c: allow error injection mm: migrate: drop unused argument of migrate_page_move_mapping() blkdev: avoid migration stalls for blkdev pages mm: migrate: provide buffer_migrate_page_norefs() mm: migrate: move migrate_page_lock_buffers() mm: migrate: lock buffers before migrate_page_move_mapping() mm: migration: factor out code to compute expected number of page references mm, page_alloc: enable pcpu_drain with zone capability kmemleak: add config to select auto scan mm/page_alloc.c: don't call kasan_free_pages() at deferred mem init ...
2018-12-28mm: convert totalram_pages and totalhigh_pages variables to atomicArun KS1-1/+1
totalram_pages and totalhigh_pages are made static inline function. Main motivation was that managed_page_count_lock handling was complicating things. It was discussed in length here, https://lore.kernel.org/patchwork/patch/995739/#1181785 So it seemes better to remove the lock and convert variables to atomic, with preventing poteintial store-to-read tearing as a bonus. [akpm@linux-foundation.org: coding style fixes] Link: http://lkml.kernel.org/r/1542090790-21750-4-git-send-email-arunks@codeaurora.org Signed-off-by: Arun KS <arunks@codeaurora.org> Suggested-by: Michal Hocko <mhocko@suse.com> Suggested-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-18dm bufio: update comment in dm-bufio.cShenghui Wang1-6/+6
* Hashtable has been replaced by rbtree to manage buffers. Update the comment. * Fix typo in the comment for dm_bufio_issue_flush Signed-off-by: Shenghui Wang <shhuiw@foxmail.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-04-30dm bufio: fix buffer alignmentMikulas Patocka1-2/+3
Commit 6b5e718cc138 ("dm bufio: relax alignment constraint on slab cache") relaxed alignment on dm-bufio cache, however it may break dm-crypt or dm-integrity. dm-crypt and dm-integrity require that the size of bio vector entries (bv_len) is aligned on its sector size. bv_offset doesn't have to be aligned, but bv_len must be. XFS sends unaligned bios, but they do not cross page boundary, so the requirement for aligned bv_len is met. Commit 6b5e718cc138 made dm-bufio send unaligned bios that cross page boundary, this could break dm-crypt and dm-integrity. Reinstates the alignment. Note that misaligned entries only happen when we use slab/slub debugging. Without debugging, the entries are always aligned. Fixes: 6b5e718cc138 ("dm bufio: relax alignment constraint on slab cache") Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-04-03dm bufio: don't embed a bio in the dm_buffer structureMikulas Patocka1-60/+45
The bio structure consumes a substantial part of dm_buffer. The bio structure is only needed when doing I/O on the buffer, thus we don't have to embed it in the buffer. Allocate the bio structure only when doing I/O. We don't need to create a bio_set because, in case of allocation failure, dm-bufio falls back to using dm-io (which keeps its own bio_set). Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-04-03dm bufio: support non-power-of-two block sizesMikulas Patocka1-25/+39
Support block sizes that are not a power-of-two (but they must be a multiple of 512b). As always, a slab cache is used for allocations. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-04-03dm bufio: use slab cache for dm_buffer structure allocationsMikulas Patocka1-9/+19
kmalloc padded to the next power of two, using a slab cache avoids this. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-04-03dm bufio: reorder fields in dm_buffer structureMikulas Patocka1-5/+5
Reorder fields in dm_buffer structure to improve packing and reduce structure size. The compiler allocates 32-bit integer for field 'enum data_mode', so change it to unsigned char. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-04-03dm bufio: relax alignment constraint on slab cacheMikulas Patocka1-2/+2
The I/O buffer doesn't have to be aligned on block size granularity, relax alignment to ARCH_KMALLOC_MINALIGN (required to allow DMA from slab cache memory on some architectures). Also, set SLAB_RECLAIM_ACCOUNT so that the memory allocated from the cache is accounted as reclaimable and doesn't inflate the 'used' entry in the free command. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-04-03dm bufio: remove code that merges slab cachesMikulas Patocka1-39/+14
All slab allocators can merge duplicate caches. So dm-bufio doesn't need extra slab merging logic. Instead it can just allocate one slab cache per client and let the allocator merge them. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-04-03dm bufio: get rid of slab cache name allocationsMikulas Patocka1-18/+3
dm-bufio keeps the dm_bufio_cache_names array that holds names of the slab caches. Since the commit db265eca7700 ("mm/sl[aou]b: Move duping of slab name to slab_common.c"), the kernel automatically duplicates the slab cache name when creating the slab cache, so we no longer have to keep the name allocated. Remove the code that allocates the slab names and keeps them around. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-04-03dm bufio: move dm-bufio.h to include/linux/Mikulas Patocka1-4/+4
Move dm-bufio.h to include/linux/ so that external GPL'd DM target modules can use it. It is better to allow the use of dm-bufio than force external modules to implement the equivalent buffered IO mechanism in some new way. The hope is this will encourage the use of dm-bufio; which will then make it easier for a GPL'd external DM target module to be included upstream. A couple dm-bufio EXPORT_SYMBOL exports have also been updated to use EXPORT_SYMBOL_GPL. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-04-03dm bufio: delete outdated commentMikulas Patocka1-4/+0
This comment was true when dm-bufio was written but, since 4.3, bios can now have arbitrary size and the driver splits them. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-03-07dm bufio: avoid false-positive Wmaybe-uninitialized warningArnd Bergmann1-10/+6
gcc-6.3 and earlier show a new warning after a seemingly unrelated change to the arm64 PAGE_KERNEL definition: In file included from drivers/md/dm-bufio.c:14:0: drivers/md/dm-bufio.c: In function 'alloc_buffer': include/linux/sched/mm.h:182:56: warning: 'noio_flag' may be used uninitialized in this function [-Wmaybe-uninitialized] current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags; ^ The same warning happened earlier on linux-3.18 for MIPS and I did a workaround for that, but now it's come back. gcc-7 and newer are apparently smart enough to figure this out, and other architectures don't show it, so the best I could come up with is to rework the caller slightly in a way that makes it obvious enough to all arm64 compilers what is happening here. Fixes: 41acec624087 ("arm64: kpti: Make use of nG dependent on arm64_kernel_unmapped_at_el0()") Link: https://patchwork.kernel.org/patch/9692829/ Cc: stable@vger.kernel.org Signed-off-by: Arnd Bergmann <arnd@arndb.de> [snitzer: moved declarations inside conditional, altered vmalloc return] Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-01-17dm bufio: eliminate unnecessary labels in dm_bufio_client_create()Mike Snitzer1-7/+5
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-01-17dm bufio: check result of register_shrinker()Aliaksei Karaliou1-6/+9
dm_bufio_client_create() does not check result of register_shrinker() which was tagged as __must_check recently, reported by sparse. Signed-off-by: Aliaksei Karaliou <akaraliou.dev@gmail.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-01-17dm bufio: add missed destroys of client mutexAliaksei Karaliou1-0/+2
The client's mutex needs to be destroyed in dm_bufio_client_destroy() as well as the dm_bufio_client_create() error path. Signed-off-by: Aliaksei Karaliou <akaraliou.dev@gmail.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2018-01-17dm bufio: use REQ_OP_READ and REQ_OP_WRITEMikulas Patocka1-6/+6
Use REQ_OP_READ and REQ_OP_WRITE macros instead of READ and WRITE. They have the same value, but the block layer uses REQ_OP so bufio should too. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2017-12-08dm bufio: fix shrinker scans when (nr_to_scan < retain_target)Suren Baghdasaryan1-2/+6
When system is under memory pressure it is observed that dm bufio shrinker often reclaims only one buffer per scan. This change fixes the following two issues in dm bufio shrinker that cause this behavior: 1. ((nr_to_scan - freed) <= retain_target) condition is used to terminate slab scan process. This assumes that nr_to_scan is equal to the LRU size, which might not be correct because do_shrink_slab() in vmscan.c calculates nr_to_scan using multiple inputs. As a result when nr_to_scan is less than retain_target (64) the scan will terminate after the first iteration, effectively reclaiming one buffer per scan and making scans very inefficient. This hurts vmscan performance especially because mutex is acquired/released every time dm_bufio_shrink_scan() is called. New implementation uses ((LRU size - freed) <= retain_target) condition for scan termination. LRU size can be safely determined inside __scan() because this function is called after dm_bufio_lock(). 2. do_shrink_slab() uses value returned by dm_bufio_shrink_count() to determine number of freeable objects in the slab. However dm_bufio always retains retain_target buffers in its LRU and will terminate a scan when this mark is reached. Therefore returning the entire LRU size from dm_bufio_shrink_count() is misleading because that does not represent the number of freeable objects that slab will reclaim during a scan. Returning (LRU size - retain_target) better represents the number of freeable objects in the slab. This way do_shrink_slab() returns 0 when (LRU size < retain_target) and vmscan will not try to scan this shrinker avoiding scans that will not reclaim any memory. Test: tested using Android device running <AOSP>/system/extras/alloc-stress that generates memory pressure and causes intensive shrinker scans Signed-off-by: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2017-11-17Merge tag 'for-4.15/dm-changes-2' of ↵Linus Torvalds1-9/+6
git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm Pull more device mapper updates from Mike Snitzer: "Given your expected travel I figured I'd get these fixes to you sooner rather than later. - a DM multipath stable@ fix to silence an annoying error message that isn't _really_ an error - a DM core @stable fix for discard support that was enabled for an entire DM device despite only having partial support for discards due to a mix of discard capabilities across the underlying devices. - a couple other DM core discard fixes. - a DM bufio @stable fix that resolves a 32-bit overflow" * tag 'for-4.15/dm-changes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: dm bufio: fix integer overflow when limiting maximum cache size dm: clear all discard attributes in queue_limits when discards are disabled dm: do not set 'discards_supported' in targets that do not need it dm: discard support requires all targets in a table support discards dm mpath: remove annoying message of 'blk_get_request() returned -11'
2017-11-17dm bufio: fix integer overflow when limiting maximum cache sizeEric Biggers1-9/+6
The default max_cache_size_bytes for dm-bufio is meant to be the lesser of 25% of the size of the vmalloc area and 2% of the size of lowmem. However, on 32-bit systems the intermediate result in the expression (VMALLOC_END - VMALLOC_START) * DM_BUFIO_VMALLOC_PERCENT / 100 overflows, causing the wrong result to be computed. For example, on a 32-bit system where the vmalloc area is 520093696 bytes, the result is 1174405 rather than the expected 130023424, which makes the maximum cache size much too small (far less than 2% of lowmem). This causes severe performance problems for dm-verity users on affected systems. Fix this by using mult_frac() to correctly multiply by a percentage. Do this for all places in dm-bufio that multiply by a percentage. Also replace (VMALLOC_END - VMALLOC_START) with VMALLOC_TOTAL, which contrary to the comment is now defined in include/linux/vmalloc.h. Depends-on: 9993bc635 ("sched/x86: Fix overflow in cyc2ns_offset") Fixes: 95d402f057f2 ("dm: add bufio") Cc: <stable@vger.kernel.org> # v3.2+ Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2017-10-25locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns ↵Mark Rutland1-5/+5
to READ_ONCE()/WRITE_ONCE() Please do not apply this to mainline directly, instead please re-run the coccinelle script shown below and apply its output. For several reasons, it is desirable to use {READ,WRITE}_ONCE() in preference to ACCESS_ONCE(), and new code is expected to use one of the former. So far, there's been no reason to change most existing uses of ACCESS_ONCE(), as these aren't harmful, and changing them results in churn. However, for some features, the read/write distinction is critical to correct operation. To distinguish these cases, separate read/write accessors must be used. This patch migrates (most) remaining ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following coccinelle script: ---- // Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and // WRITE_ONCE() // $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch virtual patch @ depends on patch @ expression E1, E2; @@ - ACCESS_ONCE(E1) = E2 + WRITE_ONCE(E1, E2) @ depends on patch @ expression E; @@ - ACCESS_ONCE(E) + READ_ONCE(E) ---- Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: davem@davemloft.net Cc: linux-arch@vger.kernel.org Cc: mpe@ellerman.id.au Cc: shuah@kernel.org Cc: snitzer@redhat.com Cc: thor.thayer@linux.intel.com Cc: tj@kernel.org Cc: viro@zeniv.linux.org.uk Cc: will.deacon@arm.com Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-09-14Merge tag 'for-4.14/dm-changes' of ↵Linus Torvalds1-28/+67
git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm Pull device mapper updates from Mike Snitzer: - Some request-based DM core and DM multipath fixes and cleanups - Constify a few variables in DM core and DM integrity - Add bufio optimization and checksum failure accounting to DM integrity - Fix DM integrity to avoid checking integrity of failed reads - Fix DM integrity to use init_completion - A couple DM log-writes target fixes - Simplify DAX flushing by eliminating the unnecessary flush abstraction that was stood up for DM's use. * tag 'for-4.14/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: dax: remove the pmem_dax_ops->flush abstraction dm integrity: use init_completion instead of COMPLETION_INITIALIZER_ONSTACK dm integrity: make blk_integrity_profile structure const dm integrity: do not check integrity for failed read operations dm log writes: fix >512b sectorsize support dm log writes: don't use all the cpu while waiting to log blocks dm ioctl: constify ioctl lookup table dm: constify argument arrays dm integrity: count and display checksum failures dm integrity: optimize writing dm-bufio buffers that are partially changed dm rq: do not update rq partially in each ending bio dm rq: make dm-sq requeuing behavior consistent with dm-mq behavior dm mpath: complain about unsupported __multipath_map_bio() return values dm mpath: avoid that building with W=1 causes gcc 7 to complain about fall-through
2017-08-28dm integrity: optimize writing dm-bufio buffers that are partially changedMikulas Patocka1-28/+67
Rather than write the entire dm-bufio buffer when only a subset is changed, improve dm-bufio (and dm-integrity) by only writing the subset of the buffer that changed. Update dm-integrity to make use of dm-bufio's new dm_bufio_mark_partial_buffer_dirty() interface. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2017-08-23block: replace bi_bdev with a gendisk pointer and partitions indexChristoph Hellwig1-1/+1
This way we don't need a block_device structure to submit I/O. The block_device has different life time rules from the gendisk and request_queue and is usually only available when the block device node is open. Other callers need to explicitly create one (e.g. the lightnvm passthrough code, or the new nvme multipathing code). For the actual I/O path all that we need is the gendisk, which exists once per block device. But given that the block layer also does partition remapping we additionally need a partition index, which is used for said remapping in generic_make_request. Note that all the block drivers generally want request_queue or sometimes the gendisk, so this removes a layer of indirection all over the stack. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-07-25dm bufio: fix error code in dm_bufio_write_dirty_buffers()Dan Carpenter1-2/+1
We should be returning normal negative error codes here. The "a" variables comes from &c->async_write_error which is a blk_status_t converted to a regular error code. In the current code, the blk_status_t gets propogated back to pool_create() and eventually results in an Oops. Fixes: 4e4cbee93d56 ("block: switch bios to blk_status_t") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2017-06-12Merge tag 'v4.12-rc5' into for-4.13/blockJens Axboe1-1/+1
We've already got a few conflicts and upcoming work depends on some of the changes that have gone into mainline as regression fixes for this series. Pull in 4.12-rc5 to resolve these conflicts and make it easier on down stream trees to continue working on 4.13 changes. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-06-09block: switch bios to blk_status_tChristoph Hellwig1-13/+15
Replace bi_error with a new bi_status to allow for a clear conversion. Note that device mapper overloaded bi_error with a private value, which we'll have to keep arround at least for now and thus propagate to a proper blk_status_t value. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-05-31dm: make flush bios explicitly syncJan Kara1-1/+1
Commit b685d3d65ac7 ("block: treat REQ_FUA and REQ_PREFLUSH as synchronous") removed REQ_SYNC flag from WRITE_{FUA|PREFLUSH|...} definitions. generic_make_request_checks() however strips REQ_FUA and REQ_PREFLUSH flags from a bio when the storage doesn't report volatile write cache and thus write effectively becomes asynchronous which can lead to performance regressions. Fix the problem by making sure all bios which are synchronous are properly marked with REQ_SYNC. Fixes: b685d3d65ac7 ("block: treat REQ_FUA and REQ_PREFLUSH as synchronous") Cc: stable@vger.kernel.org Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2017-05-16dm bufio: make the parameter "retain_bytes" unsigned longMikulas Patocka1-8/+8
Change the type of the parameter "retain_bytes" from unsigned to unsigned long, so that on 64-bit machines the user can set more than 4GiB of data to be retained. Also, change the type of the variable "count" in the function "__evict_old_buffers" to unsigned long. The assignment "count = c->n_buffers[LIST_CLEAN] + c->n_buffers[LIST_DIRTY];" could result in unsigned long to unsigned overflow and that could result in buffers not being freed when they should. While at it, avoid division in get_retain_buffers(). Division is slow, we can change it to shift because we have precalculated the log2 of block size. Cc: stable@vger.kernel.org Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2017-05-09mm, vmalloc: use __GFP_HIGHMEM implicitlyMichal Hocko1-1/+1
__vmalloc* allows users to provide gfp flags for the underlying allocation. This API is quite popular $ git grep "=[[:space:]]__vmalloc\|return[[:space:]]*__vmalloc" | wc -l 77 The only problem is that many people are not aware that they really want to give __GFP_HIGHMEM along with other flags because there is really no reason to consume precious lowmemory on CONFIG_HIGHMEM systems for pages which are mapped to the kernel vmalloc space. About half of users don't use this flag, though. This signals that we make the API unnecessarily too complex. This patch simply uses __GFP_HIGHMEM implicitly when allocating pages to be mapped to the vmalloc space. Current users which add __GFP_HIGHMEM are simplified and drop the flag. Link: http://lkml.kernel.org/r/20170307141020.29107-1-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: David Rientjes <rientjes@google.com> Cc: Cristopher Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-05-01dm bufio: check new buffer allocation watermark every 30 secondsMikulas Patocka1-0/+10
dm-bufio checks a watermark when it allocates a new buffer in __bufio_new(). However, it doesn't check the watermark when the user changes /sys/module/dm_bufio/parameters/max_cache_size_bytes. This may result in a problem - if the watermark is high enough so that all possible buffers are allocated and if the user lowers the value of "max_cache_size_bytes", the watermark will never be checked against the new value because no new buffer would be allocated. To fix this, change __evict_old_buffers() so that it checks the watermark. __evict_old_buffers() is called every 30 seconds, so if the user reduces "max_cache_size_bytes", dm-bufio will react to this change within 30 seconds and decrease memory consumption. Depends-on: 1b0fb5a5b2 ("dm bufio: avoid a possible ABBA deadlock") Cc: stable@vger.kernel.org Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2017-05-01dm bufio: avoid a possible ABBA deadlockMikulas Patocka1-4/+5
__get_memory_limit() tests if dm_bufio_cache_size changed and calls __cache_size_refresh() if it did. It takes dm_bufio_clients_lock while it already holds the client lock. However, lock ordering is violated because in cleanup_old_buffers() dm_bufio_clients_lock is taken before the client lock. This results in a possible deadlock and lockdep engine warning. Fix this deadlock by changing mutex_lock() to mutex_trylock(). If the lock can't be taken, it will be re-checked next time when a new buffer is allocated. Also add "unlikely" to the if condition, so that the optimizer assumes that the condition is false. Cc: stable@vger.kernel.org Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2017-03-07dm bufio: add sector start offset to dm-bufio interfaceMikulas Patocka1-19/+32
Introduce dm_bufio_set_sector_offset() interface to allow setting a sector offset for a dm-bufio client. This is a prereq for the DM integrity target. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Milan Broz <gmazyland@gmail.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2017-03-02sched/headers: Prepare to move the memalloc_noio_*() APIs to <linux/sched/mm.h>Ingo Molnar1-0/+1
Update the .c files that depend on these APIs. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-14sched/core: Remove set_task_state()Davidlohr Bueso1-1/+1
This is a nasty interface and setting the state of a foreign task must not be done. As of the following commit: be628be0956 ("bcache: Make gc wakeup sane, remove set_task_state()") ... everyone in the kernel calls set_task_state() with current, allowing the helper to be removed. However, as the comment indicates, it is still around for those archs where computing current is more expensive than using a pointer, at least in theory. An important arch that is affected is arm64, however this has been addressed now [1] and performance is up to par making no difference with either calls. Of all the callers, if any, it's the locking bits that would care most about this -- ie: we end up passing a tsk pointer to a lot of the lock slowpath, and setting ->state on that. The following numbers are based on two tests: a custom ad-hoc microbenchmark that just measures latencies (for ~65 million calls) between get_task_state() vs get_current_state(). Secondly for a higher overview, an unlink microbenchmark was used, which pounds on a single file with open, close,unlink combos with increasing thread counts (up to 4x ncpus). While the workload is quite unrealistic, it does contend a lot on the inode mutex or now rwsem. [1] https://lkml.kernel.org/r/1483468021-8237-1-git-send-email-mark.rutland@arm.com == 1. x86-64 == Avg runtime set_task_state(): 601 msecs Avg runtime set_current_state(): 552 msecs vanilla dirty Hmean unlink1-processes-2 36089.26 ( 0.00%) 38977.33 ( 8.00%) Hmean unlink1-processes-5 28555.01 ( 0.00%) 29832.55 ( 4.28%) Hmean unlink1-processes-8 37323.75 ( 0.00%) 44974.57 ( 20.50%) Hmean unlink1-processes-12 43571.88 ( 0.00%) 44283.01 ( 1.63%) Hmean unlink1-processes-21 34431.52 ( 0.00%) 38284.45 ( 11.19%) Hmean unlink1-processes-30 34813.26 ( 0.00%) 37975.17 ( 9.08%) Hmean unlink1-processes-48 37048.90 ( 0.00%) 39862.78 ( 7.59%) Hmean unlink1-processes-79 35630.01 ( 0.00%) 36855.30 ( 3.44%) Hmean unlink1-processes-110 36115.85 ( 0.00%) 39843.91 ( 10.32%) Hmean unlink1-processes-141 32546.96 ( 0.00%) 35418.52 ( 8.82%) Hmean unlink1-processes-172 34674.79 ( 0.00%) 36899.21 ( 6.42%) Hmean unlink1-processes-203 37303.11 ( 0.00%) 36393.04 ( -2.44%) Hmean unlink1-processes-224 35712.13 ( 0.00%) 36685.96 ( 2.73%) == 2. ppc64le == Avg runtime set_task_state(): 938 msecs Avg runtime set_current_state: 940 msecs vanilla dirty Hmean unlink1-processes-2 19269.19 ( 0.00%) 30704.50 ( 59.35%) Hmean unlink1-processes-5 20106.15 ( 0.00%) 21804.15 ( 8.45%) Hmean unlink1-processes-8 17496.97 ( 0.00%) 17243.28 ( -1.45%) Hmean unlink1-processes-12 14224.15 ( 0.00%) 17240.21 ( 21.20%) Hmean unlink1-processes-21 14155.66 ( 0.00%) 15681.23 ( 10.78%) Hmean unlink1-processes-30 14450.70 ( 0.00%) 15995.83 ( 10.69%) Hmean unlink1-processes-48 16945.57 ( 0.00%) 16370.42 ( -3.39%) Hmean unlink1-processes-79 15788.39 ( 0.00%) 14639.27 ( -7.28%) Hmean unlink1-processes-110 14268.48 ( 0.00%) 14377.40 ( 0.76%) Hmean unlink1-processes-141 14023.65 ( 0.00%) 16271.69 ( 16.03%) Hmean unlink1-processes-172 13417.62 ( 0.00%) 16067.55 ( 19.75%) Hmean unlink1-processes-203 15293.08 ( 0.00%) 15440.40 ( 0.96%) Hmean unlink1-processes-234 13719.32 ( 0.00%) 16190.74 ( 18.01%) Hmean unlink1-processes-265 16400.97 ( 0.00%) 16115.22 ( -1.74%) Hmean unlink1-processes-296 14388.60 ( 0.00%) 16216.13 ( 12.70%) Hmean unlink1-processes-320 15771.85 ( 0.00%) 15905.96 ( 0.85%) x86-64 (known to be fast for get_current()/this_cpu_read_stable() caching) and ppc64 (with paca) show similar improvements in the unlink microbenches. The small delta for ppc64 (2ms), does not represent the gains on the unlink runs. In the case of x86, there was a decent amount of variation in the latency runs, but always within a 20 to 50ms increase), ppc was more constant. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: dave@stgolabs.net Cc: mark.rutland@arm.com Link: http://lkml.kernel.org/r/1483479794-14013-5-git-send-email-dave@stgolabs.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-12-14Merge tag 'dm-4.10-changes' of ↵Linus Torvalds1-13/+15
git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm Pull device mapper updates from Mike Snitzer: - various fixes and improvements to request-based DM and DM multipath - some locking improvements in DM bufio - add Kconfig option to disable the DM block manager's extra locking which mainly serves as a developer tool - a few bug fixes to DM's persistent-data - a couple changes to prepare for multipage biovec support in the block layer - various improvements and cleanups in the DM core, DM cache, DM raid and DM crypt - add ability to have DM crypt use keys from the kernel key retention service - add a new "error_writes" feature to the DM flakey target, reads are left unchanged in this mode * tag 'dm-4.10-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (40 commits) dm flakey: introduce "error_writes" feature dm cache policy smq: use hash_32() instead of hash_32_generic() dm crypt: reject key strings containing whitespace chars dm space map: always set ev if sm_ll_mutate() succeeds dm space map metadata: skip useless memcpy in metadata_ll_init_index() dm space map metadata: fix 'struct sm_metadata' leak on failed create Documentation: dm raid: define data_offset status field dm raid: fix discard support regression dm raid: don't allow "write behind" with raid4/5/6 dm mpath: use hw_handler_params if attached hw_handler is same as requested dm crypt: add ability to use keys from the kernel key retention service dm array: remove a dead assignment in populate_ablock_with_values() dm ioctl: use offsetof() instead of open-coding it dm rq: simplify use_blk_mq initialization dm: use blk_set_queue_dying() in __dm_destroy() dm bufio: drop the lock when doing GFP_NOIO allocation dm bufio: don't take the lock in dm_bufio_shrink_count dm bufio: avoid sleeping while holding the dm_bufio lock dm table: simplify dm_table_determine_type() dm table: an 'all_blk_mq' table must be loaded for a blk-mq DM device ...
2016-12-08dm bufio: drop the lock when doing GFP_NOIO allocationMikulas Patocka1-0/+10
If the first allocation attempt using GFP_NOWAIT fails, drop the lock and retry using GFP_NOIO allocation (lock is dropped because the allocation can take some time). Note that we won't do GFP_NOIO allocation when we loop for the second time, because the lock shouldn't be dropped between __wait_for_free_buffer and __get_unclaimed_buffer. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2016-12-08dm bufio: don't take the lock in dm_bufio_shrink_countMikulas Patocka1-11/+2
dm_bufio_shrink_count() is called from do_shrink_slab to find out how many freeable objects are there. The reported value doesn't have to be precise, so we don't need to take the dm-bufio lock. Suggested-by: David Rientjes <rientjes@google.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2016-12-08dm bufio: avoid sleeping while holding the dm_bufio lockDouglas Anderson1-2/+3
We've seen in-field reports showing _lots_ (18 in one case, 41 in another) of tasks all sitting there blocked on: mutex_lock+0x4c/0x68 dm_bufio_shrink_count+0x38/0x78 shrink_slab.part.54.constprop.65+0x100/0x464 shrink_zone+0xa8/0x198 In the two cases analyzed, we see one task that looks like this: Workqueue: kverityd verity_prefetch_io __switch_to+0x9c/0xa8 __schedule+0x440/0x6d8 schedule+0x94/0xb4 schedule_timeout+0x204/0x27c schedule_timeout_uninterruptible+0x44/0x50 wait_iff_congested+0x9c/0x1f0 shrink_inactive_list+0x3a0/0x4cc shrink_lruvec+0x418/0x5cc shrink_zone+0x88/0x198 try_to_free_pages+0x51c/0x588 __alloc_pages_nodemask+0x648/0xa88 __get_free_pages+0x34/0x7c alloc_buffer+0xa4/0x144 __bufio_new+0x84/0x278 dm_bufio_prefetch+0x9c/0x154 verity_prefetch_io+0xe8/0x10c process_one_work+0x240/0x424 worker_thread+0x2fc/0x424 kthread+0x10c/0x114 ...and that looks to be the one holding the mutex. The problem has been reproduced on fairly easily: 0. Be running Chrome OS w/ verity enabled on the root filesystem 1. Pick test patch: http://crosreview.com/412360 2. Install launchBalloons.sh and balloon.arm from http://crbug.com/468342 ...that's just a memory stress test app. 3. On a 4GB rk3399 machine, run nice ./launchBalloons.sh 4 900 100000 ...that tries to eat 4 * 900 MB of memory and keep accessing. 4. Login to the Chrome web browser and restore many tabs With that, I've seen printouts like: DOUG: long bufio 90758 ms ...and stack trace always show's we're in dm_bufio_prefetch(). The problem is that we try to allocate memory with GFP_NOIO while we're holding the dm_bufio lock. Instead we should be using GFP_NOWAIT. Using GFP_NOIO can cause us to sleep while holding the lock and that causes the above problems. The current behavior explained by David Rientjes: It will still try reclaim initially because __GFP_WAIT (or __GFP_KSWAPD_RECLAIM) is set by GFP_NOIO. This is the cause of contention on dm_bufio_lock() that the thread holds. You want to pass GFP_NOWAIT instead of GFP_NOIO to alloc_buffer() when holding a mutex that can be contended by a concurrent slab shrinker (if count_objects didn't use a trylock, this pattern would trivially deadlock). This change significantly increases responsiveness of the system while in this state. It makes a real difference because it unblocks kswapd. In the bug report analyzed, kswapd was hung: kswapd0 D ffffffc000204fd8 0 72 2 0x00000000 Call trace: [<ffffffc000204fd8>] __switch_to+0x9c/0xa8 [<ffffffc00090b794>] __schedule+0x440/0x6d8 [<ffffffc00090bac0>] schedule+0x94/0xb4 [<ffffffc00090be44>] schedule_preempt_disabled+0x28/0x44 [<ffffffc00090d900>] __mutex_lock_slowpath+0x120/0x1ac [<ffffffc00090d9d8>] mutex_lock+0x4c/0x68 [<ffffffc000708e7c>] dm_bufio_shrink_count+0x38/0x78 [<ffffffc00030b268>] shrink_slab.part.54.constprop.65+0x100/0x464 [<ffffffc00030dbd8>] shrink_zone+0xa8/0x198 [<ffffffc00030e578>] balance_pgdat+0x328/0x508 [<ffffffc00030eb7c>] kswapd+0x424/0x51c [<ffffffc00023f06c>] kthread+0x10c/0x114 [<ffffffc000203dd0>] ret_from_fork+0x10/0x40 By unblocking kswapd memory pressure should be reduced. Suggested-by: David Rientjes <rientjes@google.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Douglas Anderson <dianders@chromium.org> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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