kernel/linux.git/include/linux/slab_def.h, branch v6.6.131

mm/kasan: simplify and refine kasan_cache code

2023-01-19T01:12:55+00:00

struct 'kasan_cache' has a member 'is_kmalloc' indicating whether its host kmem_cache is a kmalloc cache. With newly introduced is_kmalloc_cache() helper, 'is_kmalloc' and its related function can be replaced and removed. Also 'kasan_cache' is only needed by KASAN generic mode, and not by SW/HW tag modes, so refine its protection macro accordingly, suggested by Andrey Konoval. Link: https://lkml.kernel.org/r/20230104060605.930910-2-feng.tang@intel.com Signed-off-by: Feng Tang Reviewed-by: Andrey Konovalov Acked-by: Vlastimil Babka Acked-by: David Rientjes Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Christoph Lameter Cc: Dmitry Vyukov Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Joonsoo Kim Cc: Pekka Enberg Cc: Roman Gushchin Cc: Vincenzo Frascino Signed-off-by: Andrew Morton

mm, slab: ignore hardened usercopy parameters when disabled

2022-11-27T22:35:04+00:00

With CONFIG_HARDENED_USERCOPY not enabled, there are no __check_heap_object() checks happening that would use the struct kmem_cache useroffset and usersize fields. Yet the fields are still initialized, preventing merging of otherwise compatible caches. Also the fields contribute to struct kmem_cache size unnecessarily when unused. Thus #ifdef them out completely when CONFIG_HARDENED_USERCOPY is disabled. In kmem_dump_obj() print object_size instead of usersize, as that's actually the intention. In a quick virtme boot test, this has reduced the number of caches in /proc/slabinfo from 131 to 111. Cc: Kees Cook Signed-off-by: Vlastimil Babka Acked-by: Roman Gushchin Acked-by: Mike Rapoport Reviewed-by: Christoph Lameter

mm/slab: use kmalloc_node() for off slab freelist_idx_t array allocation

2022-10-15T19:42:05+00:00

After commit d6a71648dbc0 ("mm/slab: kmalloc: pass requests larger than order-1 page to page allocator"), SLAB passes large ( > PAGE_SIZE * 2) requests to buddy like SLUB does. SLAB has been using kmalloc caches to allocate freelist_idx_t array for off slab caches. But after the commit, freelist_size can be bigger than KMALLOC_MAX_CACHE_SIZE. Instead of using pointer to kmalloc cache, use kmalloc_node() and only check if the kmalloc cache is off slab during calculate_slab_order(). If freelist_size > KMALLOC_MAX_CACHE_SIZE, no looping condition happens as it allocates freelist_idx_t array directly from buddy. Link: https://lore.kernel.org/all/20221014205818.GA1428667@roeck-us.net/ Reported-and-tested-by: Guenter Roeck Fixes: d6a71648dbc0 ("mm/slab: kmalloc: pass requests larger than order-1 page to page allocator") Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Signed-off-by: Vlastimil Babka

mm: Convert struct page to struct slab in functions used by other subsystems

2022-01-06T11:26:13+00:00

KASAN, KFENCE and memcg interact with SLAB or SLUB internals through functions nearest_obj(), obj_to_index() and objs_per_slab() that use struct page as parameter. This patch converts it to struct slab including all callers, through a coccinelle semantic patch. // Options: --include-headers --no-includes --smpl-spacing include/linux/slab_def.h include/linux/slub_def.h mm/slab.h mm/kasan/*.c mm/kfence/kfence_test.c mm/memcontrol.c mm/slab.c mm/slub.c // Note: needs coccinelle 1.1.1 to avoid breaking whitespace @@ @@ -objs_per_slab_page( +objs_per_slab( ... ) { ... } @@ @@ -objs_per_slab_page( +objs_per_slab( ... ) @@ identifier fn =~ "obj_to_index|objs_per_slab"; @@ fn(..., - const struct page *page + const struct slab *slab ,...) { <... ( - page_address(page) + slab_address(slab) | - page + slab ) ...> } @@ identifier fn =~ "nearest_obj"; @@ fn(..., - struct page *page + const struct slab *slab ,...) { <... ( - page_address(page) + slab_address(slab) | - page + slab ) ...> } @@ identifier fn =~ "nearest_obj|obj_to_index|objs_per_slab"; expression E; @@ fn(..., ( - slab_page(E) + E | - virt_to_page(E) + virt_to_slab(E) | - virt_to_head_page(E) + virt_to_slab(E) | - page + page_slab(page) ) ,...) Signed-off-by: Vlastimil Babka Reviewed-by: Andrey Konovalov Reviewed-by: Roman Gushchin Acked-by: Johannes Weiner Cc: Julia Lawall Cc: Luis Chamberlain Cc: Andrey Ryabinin Cc: Alexander Potapenko Cc: Andrey Konovalov Cc: Dmitry Vyukov Cc: Marco Elver Cc: Johannes Weiner Cc: Michal Hocko Cc: Vladimir Davydov Cc: Cc:

mm, kfence: insert KFENCE hooks for SLAB

2021-02-26T17:41:02+00:00

Inserts KFENCE hooks into the SLAB allocator. To pass the originally requested size to KFENCE, add an argument 'orig_size' to slab_alloc*(). The additional argument is required to preserve the requested original size for kmalloc() allocations, which uses size classes (e.g. an allocation of 272 bytes will return an object of size 512). Therefore, kmem_cache::size does not represent the kmalloc-caller's requested size, and we must introduce the argument 'orig_size' to propagate the originally requested size to KFENCE. Without the originally requested size, we would not be able to detect out-of-bounds accesses for objects placed at the end of a KFENCE object page if that object is not equal to the kmalloc-size class it was bucketed into. When KFENCE is disabled, there is no additional overhead, since slab_alloc*() functions are __always_inline. Link: https://lkml.kernel.org/r/20201103175841.3495947-5-elver@google.com Signed-off-by: Marco Elver Signed-off-by: Alexander Potapenko Reviewed-by: Dmitry Vyukov Co-developed-by: Marco Elver Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Cc: Andrey Konovalov Cc: Andrey Ryabinin Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Catalin Marinas Cc: Dave Hansen Cc: Eric Dumazet Cc: Greg Kroah-Hartman Cc: Hillf Danton Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Jann Horn Cc: Joern Engel Cc: Jonathan Corbet Cc: Kees Cook Cc: Mark Rutland Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: SeongJae Park Cc: Thomas Gleixner Cc: Vlastimil Babka Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: memcg/slab: use a single set of kmem_caches for all allocations

2020-08-07T18:33:25+00:00

Instead of having two sets of kmem_caches: one for system-wide and non-accounted allocations and the second one shared by all accounted allocations, we can use just one. The idea is simple: space for obj_cgroup metadata can be allocated on demand and filled only for accounted allocations. It allows to remove a bunch of code which is required to handle kmem_cache clones for accounted allocations. There is no more need to create them, accumulate statistics, propagate attributes, etc. It's a quite significant simplification. Also, because the total number of slab_caches is reduced almost twice (not all kmem_caches have a memcg clone), some additional memory savings are expected. On my devvm it additionally saves about 3.5% of slab memory. [guro@fb.com: fix build on MIPS] Link: http://lkml.kernel.org/r/20200717214810.3733082-1-guro@fb.com Suggested-by: Johannes Weiner Signed-off-by: Roman Gushchin Signed-off-by: Andrew Morton Reviewed-by: Vlastimil Babka Reviewed-by: Shakeel Butt Cc: Christoph Lameter Cc: Michal Hocko Cc: Tejun Heo Cc: Naresh Kamboju Link: http://lkml.kernel.org/r/20200623174037.3951353-18-guro@fb.com Signed-off-by: Linus Torvalds

mm: memcg/slab: allocate obj_cgroups for non-root slab pages

2020-08-07T18:33:24+00:00

Allocate and release memory to store obj_cgroup pointers for each non-root slab page. Reuse page->mem_cgroup pointer to store a pointer to the allocated space. This commit temporarily increases the memory footprint of the kernel memory accounting. To store obj_cgroup pointers we'll need a place for an objcg_pointer for each allocated object. However, the following patches in the series will enable sharing of slab pages between memory cgroups, which will dramatically increase the total slab utilization. And the final memory footprint will be significantly smaller than before. To distinguish between obj_cgroups and memcg pointers in case when it's not obvious which one is used (as in page_cgroup_ino()), let's always set the lowest bit in the obj_cgroup case. The original obj_cgroups pointer is marked to be ignored by kmemleak, which otherwise would report a memory leak for each allocated vector. Signed-off-by: Roman Gushchin Signed-off-by: Andrew Morton Reviewed-by: Vlastimil Babka Reviewed-by: Shakeel Butt Cc: Christoph Lameter Cc: Johannes Weiner Cc: Michal Hocko Cc: Tejun Heo Link: http://lkml.kernel.org/r/20200623174037.3951353-8-guro@fb.com Signed-off-by: Linus Torvalds

slab: remove /proc/slab_allocators

2019-05-16T22:51:55+00:00

It turned out that DEBUG_SLAB_LEAK is still broken even after recent recue efforts that when there is a large number of objects like kmemleak_object which is normal on a debug kernel, # grep kmemleak /proc/slabinfo kmemleak_object 2243606 3436210 ... reading /proc/slab_allocators could easily loop forever while processing the kmemleak_object cache and any additional freeing or allocating objects will trigger a reprocessing. To make a situation worse, soft-lockups could easily happen in this sitatuion which will call printk() to allocate more kmemleak objects to guarantee an infinite loop. Also, since it seems no one had noticed when it was totally broken more than 2-year ago - see the commit fcf88917dd43 ("slab: fix a crash by reading /proc/slab_allocators"), probably nobody cares about it anymore due to the decline of the SLAB. Just remove it entirely. Suggested-by: Vlastimil Babka Suggested-by: Linus Torvalds Signed-off-by: Qian Cai Signed-off-by: Linus Torvalds

mm: move obj_to_index to include/linux/slab_def.h

2018-12-28T20:11:44+00:00

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 Reviewed-by: Andrey Ryabinin Reviewed-by: Dmitry Vyukov Acked-by: Christoph Lameter Cc: Mark Rutland Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

slab: clean up the code comment in slab kmem_cache struct

2018-06-08T00:34:34+00:00

In commit 3b0efdfa1e7 ("mm, sl[aou]b: Extract common fields from struct kmem_cache") the variable 'obj_size' was moved above, however the related code comment is not updated accordingly. Do it here. Link: http://lkml.kernel.org/r/20180603032402.27526-1-bhe@redhat.com Signed-off-by: Baoquan He Reviewed-by: Andrew Morton Acked-by: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds