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2025-11-07slab: prevent recursive kmalloc() in alloc_empty_sheaf()Vlastimil Babka
We want to expand usage of sheaves to all non-boot caches, including kmalloc caches. Since sheaves themselves are also allocated by kmalloc(), we need to prevent excessive or infinite recursion - depending on sheaf size, the sheaf can be allocated from smaller, same or larger kmalloc size bucket, there's no particular constraint. This is similar to allocating the objext arrays so let's just reuse the existing mechanisms for those. __GFP_NO_OBJ_EXT in alloc_empty_sheaf() will prevent a nested kmalloc() from allocating a sheaf itself - it will either have sheaves already, or fallback to a non-sheaf-cached allocation (so bootstrap of sheaves in a kmalloc cache that allocates sheaves from its own size bucket is possible). Additionally, reuse OBJCGS_CLEAR_MASK to clear unwanted gfp flags from the nested allocation. Link: https://patch.msgid.link/20251105-sheaves-cleanups-v1-5-b8218e1ac7ef@suse.cz Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
2024-09-09mm: warn about illegal __GFP_NOFAIL usage in a more appropriate location and ↵Barry Song
manner Three points for this change: 1. We should consolidate all warnings in one place. Currently, the order > 1 warning is in the hotpath, while others are in less likely scenarios. Moving all warnings to the slowpath will reduce the overhead for order > 1 and increase the visibility of other warnings. 2. We currently have two warnings for order: one for order > 1 in the hotpath and another for order > costly_order in the laziest path. I suggest standardizing on order > 1 since it's been in use for a long time. 3. We don't need to check for __GFP_NOWARN in this case. __GFP_NOWARN is meant to suppress allocation failure reports, but here we're dealing with bug detection, not allocation failures. So replace WARN_ON_ONCE_GFP by WARN_ON_ONCE. [v-songbaohua@oppo.com: also update the doc for __GFP_NOFAIL with order > 1] Link: https://lkml.kernel.org/r/20240903223935.1697-1-21cnbao@gmail.com Link: https://lkml.kernel.org/r/20240830202823.21478-4-21cnbao@gmail.com Signed-off-by: Barry Song <v-songbaohua@oppo.com> Suggested-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: David Hildenbrand <david@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Christoph Lameter <cl@linux.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: David Rientjes <rientjes@google.com> Cc: "Eugenio Pérez" <eperezma@redhat.com> Cc: Hailong.Liu <hailong.liu@oppo.com> Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kees Cook <kees@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Cc: Maxime Coquelin <maxime.coquelin@redhat.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Uladzislau Rezki (Sony) <urezki@gmail.com> Cc: Xie Yongji <xieyongji@bytedance.com> Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com> Cc: Yafang Shao <laoar.shao@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-09-09mm: document __GFP_NOFAIL must be blockableBarry Song
Non-blocking allocation with __GFP_NOFAIL is not supported and may still result in NULL pointers (if we don't return NULL, we result in busy-loop within non-sleepable contexts): static inline struct page * __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, struct alloc_context *ac) { ... /* * Make sure that __GFP_NOFAIL request doesn't leak out and make sure * we always retry */ if (gfp_mask & __GFP_NOFAIL) { /* * All existing users of the __GFP_NOFAIL are blockable, so warn * of any new users that actually require GFP_NOWAIT */ if (WARN_ON_ONCE_GFP(!can_direct_reclaim, gfp_mask)) goto fail; ... } ... fail: warn_alloc(gfp_mask, ac->nodemask, "page allocation failure: order:%u", order); got_pg: return page; } Highlight this in the documentation of __GFP_NOFAIL so that non-mm subsystems can reject any illegal usage of __GFP_NOFAIL with GFP_ATOMIC, GFP_NOWAIT, etc. Link: https://lkml.kernel.org/r/20240830202823.21478-3-21cnbao@gmail.com Signed-off-by: Barry Song <v-songbaohua@oppo.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Davidlohr Bueso <dave@stgolabs.net> Acked-by: David Hildenbrand <david@redhat.com> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: "Eugenio Pérez" <eperezma@redhat.com> Cc: Hailong.Liu <hailong.liu@oppo.com> Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Jason Wang <jasowang@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kees Cook <kees@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Cc: Maxime Coquelin <maxime.coquelin@redhat.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Uladzislau Rezki (Sony) <urezki@gmail.com> Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Xie Yongji <xieyongji@bytedance.com> Cc: Yafang Shao <laoar.shao@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-04-25mm: introduce __GFP_NO_OBJ_EXT flag to selectively prevent slabobj_ext creationSuren Baghdasaryan
Introduce __GFP_NO_OBJ_EXT flag in order to prevent recursive allocations when allocating slabobj_ext on a slab. Link: https://lkml.kernel.org/r/20240321163705.3067592-8-surenb@google.com Signed-off-by: Suren Baghdasaryan <surenb@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Tested-by: Kees Cook <keescook@chromium.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alex Gaynor <alex.gaynor@gmail.com> Cc: Alice Ryhl <aliceryhl@google.com> Cc: Andreas Hindborg <a.hindborg@samsung.com> Cc: Benno Lossin <benno.lossin@proton.me> Cc: "Björn Roy Baron" <bjorn3_gh@protonmail.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Dennis Zhou <dennis@kernel.org> Cc: Gary Guo <gary@garyguo.net> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: Miguel Ojeda <ojeda@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Tejun Heo <tj@kernel.org> Cc: Wedson Almeida Filho <wedsonaf@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-04-04memblock tests: fix undefined reference to `BIT'Wei Yang
commit 772dd0342727 ("mm: enumerate all gfp flags") define gfp flags with the help of BIT, while gfp_types.h doesn't include header file for the definition. This through an error on building memblock tests. Let's include linux/bits.h to fix it. Signed-off-by: Wei Yang <richard.weiyang@gmail.com> CC: Suren Baghdasaryan <surenb@google.com> CC: Michal Hocko <mhocko@suse.com> Link: https://lore.kernel.org/r/20240402132701.29744-4-richard.weiyang@gmail.com Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
2024-03-04mm: enumerate all gfp flagsSuren Baghdasaryan
Introduce GFP bits enumeration to let compiler track the number of used bits (which depends on the config options) instead of hardcoding them. That simplifies __GFP_BITS_SHIFT calculation. Link: https://lkml.kernel.org/r/20240224015800.2569851-1-surenb@google.com Suggested-by: Petr Tesařík <petr@tesarici.cz> Signed-off-by: Suren Baghdasaryan <surenb@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: Petr Tesarik <petr@tesarici.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-12-20gfp: gfp_types.h: fix typos & punctuationRandy Dunlap
Correct typos/spellos and punctutation. Link: https://lkml.kernel.org/r/20231213043316.10128-1-rdunlap@infradead.org Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-12-10gfp: include __GFP_NOWARN in GFP_NOWAITMatthew Wilcox (Oracle)
GFP_NOWAIT callers are always prepared for their allocations to fail because they fail so frequently. Forcing the callers to remember to add __GFP_NOWARN is just annoying and leads to an endless stream of patches for the places where we forgot to add it. We can now remove __GFP_NOWARN from all the callers which specify GFP_NOWAIT, but I'd rather wait a cycle and send patches to each maintainer instead of creating a big pile of merge conflicts. Link: https://lkml.kernel.org/r/20231109211507.2262419-1-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-03-28kasan: remove PG_skip_kasan_poison flagPeter Collingbourne
Code inspection reveals that PG_skip_kasan_poison is redundant with kasantag, because the former is intended to be set iff the latter is the match-all tag. It can also be observed that it's basically pointless to poison pages which have kasantag=0, because any pages with this tag would have been pointed to by pointers with match-all tags, so poisoning the pages would have little to no effect in terms of bug detection. Therefore, change the condition in should_skip_kasan_poison() to check kasantag instead, and remove PG_skip_kasan_poison and associated flags. Link: https://lkml.kernel.org/r/20230310042914.3805818-3-pcc@google.com Link: https://linux-review.googlesource.com/id/I57f825f2eaeaf7e8389d6cf4597c8a5821359838 Signed-off-by: Peter Collingbourne <pcc@google.com> Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Evgenii Stepanov <eugenis@google.com> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-02mm: discard __GFP_ATOMICNeilBrown
__GFP_ATOMIC serves little purpose. Its main effect is to set ALLOC_HARDER which adds a few little boosts to increase the chance of an allocation succeeding, one of which is to lower the water-mark at which it will succeed. It is *always* paired with __GFP_HIGH which sets ALLOC_HIGH which also adjusts this watermark. It is probable that other users of __GFP_HIGH should benefit from the other little bonuses that __GFP_ATOMIC gets. __GFP_ATOMIC also gives a warning if used with __GFP_DIRECT_RECLAIM. There is little point to this. We already get a might_sleep() warning if __GFP_DIRECT_RECLAIM is set. __GFP_ATOMIC allows the "watermark_boost" to be side-stepped. It is probable that testing ALLOC_HARDER is a better fit here. __GFP_ATOMIC is used by tegra-smmu.c to check if the allocation might sleep. This should test __GFP_DIRECT_RECLAIM instead. This patch: - removes __GFP_ATOMIC - allows __GFP_HIGH allocations to ignore watermark boosting as well as GFP_ATOMIC requests. - makes other adjustments as suggested by the above. The net result is not change to GFP_ATOMIC allocations. Other allocations that use __GFP_HIGH will benefit from a few different extra privileges. This affects: xen, dm, md, ntfs3 the vermillion frame buffer hibernation ksm swap all of which likely produce more benefit than cost if these selected allocation are more likely to succeed quickly. [mgorman: Minor adjustments to rework on top of a series] Link: https://lkml.kernel.org/r/163712397076.13692.4727608274002939094@noble.neil.brown.name Link: https://lkml.kernel.org/r/20230113111217.14134-7-mgorman@techsingularity.net Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Thierry Reding <thierry.reding@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-08-07Merge tag 'bitmap-6.0-rc1' of https://github.com/norov/linuxLinus Torvalds
Pull bitmap updates from Yury Norov: - fix the duplicated comments on bitmap_to_arr64() (Qu Wenruo) - optimize out non-atomic bitops on compile-time constants (Alexander Lobakin) - cleanup bitmap-related headers (Yury Norov) - x86/olpc: fix 'logical not is only applied to the left hand side' (Alexander Lobakin) - lib/nodemask: inline wrappers around bitmap (Yury Norov) * tag 'bitmap-6.0-rc1' of https://github.com/norov/linux: (26 commits) lib/nodemask: inline next_node_in() and node_random() powerpc: drop dependency on <asm/machdep.h> in archrandom.h x86/olpc: fix 'logical not is only applied to the left hand side' lib/cpumask: move some one-line wrappers to header file headers/deps: mm: align MANITAINERS and Docs with new gfp.h structure headers/deps: mm: Split <linux/gfp_types.h> out of <linux/gfp.h> headers/deps: mm: Optimize <linux/gfp.h> header dependencies lib/cpumask: move trivial wrappers around find_bit to the header lib/cpumask: change return types to unsigned where appropriate cpumask: change return types to bool where appropriate lib/bitmap: change type of bitmap_weight to unsigned long lib/bitmap: change return types to bool where appropriate arm: align find_bit declarations with generic kernel iommu/vt-d: avoid invalid memory access via node_online(NUMA_NO_NODE) lib/test_bitmap: test the tail after bitmap_to_arr64() lib/bitmap: fix off-by-one in bitmap_to_arr64() lib: test_bitmap: add compile-time optimization/evaluations assertions bitmap: don't assume compiler evaluates small mem*() builtins calls net/ice: fix initializing the bitmap in the switch code bitops: let optimize out non-atomic bitops on compile-time constants ...
2022-07-15headers/deps: mm: Split <linux/gfp_types.h> out of <linux/gfp.h>Ingo Molnar
This is a much smaller header. Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Yury Norov <yury.norov@gmail.com>