mm/slub: disable user tracing for kmemleak caches by default
If kmemleak is enabled, it uses a kmem cache for its own objects. These objects are used to hold information kmemleak uses, including a stack trace. If slub_debug is also turned on, each of them has *another* stack trace, so the overhead adds up, and on my tests (on ARCH=um, admittedly) 2/3rds of the allocations end up being doing the stack tracing. Turn off SLAB_STORE_USER if SLAB_NOLEAKTRACE was given, to avoid storing the essentially same data twice. Link: https://lkml.kernel.org/r/20210113215114.d94efa13ba30.I117b6764e725b3192318bbcf4269b13b709539ae@changeid Signed-off-by: Johannes Berg <johannes.berg@intel.com> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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mm/slub.c
11
mm/slub.c
@ -1413,6 +1413,15 @@ slab_flags_t kmem_cache_flags(unsigned int object_size,
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size_t len;
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size_t len;
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char *next_block;
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char *next_block;
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slab_flags_t block_flags;
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slab_flags_t block_flags;
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slab_flags_t slub_debug_local = slub_debug;
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/*
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* If the slab cache is for debugging (e.g. kmemleak) then
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* don't store user (stack trace) information by default,
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* but let the user enable it via the command line below.
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*/
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if (flags & SLAB_NOLEAKTRACE)
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slub_debug_local &= ~SLAB_STORE_USER;
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len = strlen(name);
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len = strlen(name);
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next_block = slub_debug_string;
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next_block = slub_debug_string;
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@ -1447,7 +1456,7 @@ slab_flags_t kmem_cache_flags(unsigned int object_size,
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}
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}
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}
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}
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return flags | slub_debug;
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return flags | slub_debug_local;
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}
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}
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#else /* !CONFIG_SLUB_DEBUG */
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#else /* !CONFIG_SLUB_DEBUG */
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static inline void setup_object_debug(struct kmem_cache *s,
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static inline void setup_object_debug(struct kmem_cache *s,
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