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mm/slab: remove !CONFIG_TRACING variants of kmalloc_[node_]trace() 

For !CONFIG_TRACING kernels, the kmalloc() implementation tries (in cases where
the allocation size is build-time constant) to save a function call, by
inlining kmalloc_trace() to a kmem_cache_alloc() call.

However since commit 6edf2576a6 ("mm/slub: enable debugging memory wasting of
kmalloc") this path now fails to pass the original request size to be
eventually recorded (for kmalloc caches with debugging enabled).

We could adjust the code to call __kmem_cache_alloc_node() as the
CONFIG_TRACING variant, but that would as a result inline a call with 5
parameters, bloating the kmalloc() call sites. The cost of extra function
call (to kmalloc_trace()) seems like a lesser evil.

It also appears that the !CONFIG_TRACING variant is incompatible with upcoming
hardening efforts [1] so it's easier if we just remove it now. Kernels with no
tracing are rare these days and the benefit is dubious anyway.

[1] https://lore.kernel.org/linux-mm/20221101222520.never.109-kees@kernel.org/T/#m20ecf14390e406247bde0ea9cce368f469c539ed

Link: https://lore.kernel.org/all/097d8fba-bd10-a312-24a3-a4068c4f424c@suse.cz/
Suggested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
This commit is contained in:
Vlastimil Babka 2022-11-04 13:57:11 +01:00
parent a207620123
commit eb4940d4ad
2 changed files with 0 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
include/linux/slab.h
View File

@ -470,35 +470,12 @@ void *__kmalloc_node(size_t size, gfp_t flags, int node) __assume_kmalloc_alignm
void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t flags, int node) __assume_slab_alignment
__malloc;
#ifdef CONFIG_TRACING
void *kmalloc_trace(struct kmem_cache *s, gfp_t flags, size_t size)
__assume_kmalloc_alignment __alloc_size(3);
void *kmalloc_node_trace(struct kmem_cache *s, gfp_t gfpflags,
int node, size_t size) __assume_kmalloc_alignment
__alloc_size(4);
#else /* CONFIG_TRACING */
/* Save a function call when CONFIG_TRACING=n */
static __always_inline __alloc_size(3)
void *kmalloc_trace(struct kmem_cache *s, gfp_t flags, size_t size)
{
void *ret = kmem_cache_alloc(s, flags);
ret = kasan_kmalloc(s, ret, size, flags);
return ret;
}
static __always_inline __alloc_size(4)
void *kmalloc_node_trace(struct kmem_cache *s, gfp_t gfpflags,
int node, size_t size)
{
void *ret = kmem_cache_alloc_node(s, gfpflags, node);
ret = kasan_kmalloc(s, ret, size, gfpflags);
return ret;
}
#endif /* CONFIG_TRACING */
void *kmalloc_large(size_t size, gfp_t flags) __assume_page_alignment
__alloc_size(1);

2
mm/slab_common.c
View File

@ -1040,7 +1040,6 @@ size_t __ksize(const void *object)
return slab_ksize(folio_slab(folio)->slab_cache);
}
#ifdef CONFIG_TRACING
void *kmalloc_trace(struct kmem_cache *s, gfp_t gfpflags, size_t size)
{
void *ret = __kmem_cache_alloc_node(s, gfpflags, NUMA_NO_NODE,
@ -1064,7 +1063,6 @@ void *kmalloc_node_trace(struct kmem_cache *s, gfp_t gfpflags,
return ret;
}
EXPORT_SYMBOL(kmalloc_node_trace);
#endif /* !CONFIG_TRACING */
#endif /* !CONFIG_SLOB */
gfp_t kmalloc_fix_flags(gfp_t flags)