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mm, slub: change run-time assertion in kmalloc_index() to compile-time

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Currently when size is not supported by kmalloc_index, compiler will
generate a run-time BUG() while compile-time error is also possible, and
better.  So change BUG to BUILD_BUG_ON_MSG to make compile-time check
possible.

Also remove code that allocates more than 32MB because current
implementation supports only up to 32MB.

[42.hyeyoo@gmail.com: fix support for clang 10]
  Link: https://lkml.kernel.org/r/20210518181247.GA10062@hyeyoo
[vbabka@suse.cz: fix false-positive assert in kernel/bpf/local_storage.c]
  Link: https://lkml.kernel.org/r/bea97388-01df-8eac-091b-a3c89b4a4a09@suse.czLink: https://lkml.kernel.org/r/20210511173448.GA54466@hyeyoo
[elver@google.com: kfence fix]
  Link: https://lkml.kernel.org/r/20210512195227.245000695c9014242e9a00e5@linux-foundation.org

Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Marco Elver <elver@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hyeonggon Yoo 2021-06-28 19:34:39 -07:00 committed by Linus Torvalds
parent 3d8e374c6d
commit 588c7fa022
3 changed files with 20 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
include/linux/slab.h
View File

@ -346,8 +346,14 @@ static __always_inline enum kmalloc_cache_type kmalloc_type(gfp_t flags)
* 1 = 65 .. 96 bytes * 1 = 65 .. 96 bytes
* 2 = 129 .. 192 bytes * 2 = 129 .. 192 bytes
* n = 2^(n-1)+1 .. 2^n * n = 2^(n-1)+1 .. 2^n
*
* Note: __kmalloc_index() is compile-time optimized, and not runtime optimized;
* typical usage is via kmalloc_index() and therefore evaluated at compile-time.
* Callers where !size_is_constant should only be test modules, where runtime
* overheads of __kmalloc_index() can be tolerated. Also see kmalloc_slab().
*/ */
static __always_inline unsigned int kmalloc_index(size_t size) static __always_inline unsigned int __kmalloc_index(size_t size,
bool size_is_constant)
{ {
if (!size) if (!size)
return 0; return 0;
@ -382,12 +388,17 @@ static __always_inline unsigned int kmalloc_index(size_t size)
if (size <= 8 * 1024 * 1024) return 23; if (size <= 8 * 1024 * 1024) return 23;
if (size <= 16 * 1024 * 1024) return 24; if (size <= 16 * 1024 * 1024) return 24;
if (size <= 32 * 1024 * 1024) return 25; if (size <= 32 * 1024 * 1024) return 25;
if (size <= 64 * 1024 * 1024) return 26;
BUG(); if ((IS_ENABLED(CONFIG_CC_IS_GCC) || CONFIG_CLANG_VERSION >= 110000)
&& !IS_ENABLED(CONFIG_PROFILE_ALL_BRANCHES) && size_is_constant)
BUILD_BUG_ON_MSG(1, "unexpected size in kmalloc_index()");
else
BUG();
/* Will never be reached. Needed because the compiler may complain */ /* Will never be reached. Needed because the compiler may complain */
return -1; return -1;
} }
#define kmalloc_index(s) __kmalloc_index(s, true)
#endif /* !CONFIG_SLOB */ #endif /* !CONFIG_SLOB */
void *__kmalloc(size_t size, gfp_t flags) __assume_kmalloc_alignment __malloc; void *__kmalloc(size_t size, gfp_t flags) __assume_kmalloc_alignment __malloc;

5
mm/kfence/kfence_test.c
View File

@ -197,7 +197,7 @@ static void test_cache_destroy(void)
static inline size_t kmalloc_cache_alignment(size_t size) static inline size_t kmalloc_cache_alignment(size_t size)
{ {
return kmalloc_caches[kmalloc_type(GFP_KERNEL)][kmalloc_index(size)]->align; return kmalloc_caches[kmalloc_type(GFP_KERNEL)][__kmalloc_index(size, false)]->align;
} }
/* Must always inline to match stack trace against caller. */ /* Must always inline to match stack trace against caller. */
@ -267,7 +267,8 @@ static void *test_alloc(struct kunit *test, size_t size, gfp_t gfp, enum allocat
if (is_kfence_address(alloc)) { if (is_kfence_address(alloc)) {
struct page *page = virt_to_head_page(alloc); struct page *page = virt_to_head_page(alloc);
struct kmem_cache *s = test_cache ?: kmalloc_caches[kmalloc_type(GFP_KERNEL)][kmalloc_index(size)]; struct kmem_cache *s = test_cache ?:
kmalloc_caches[kmalloc_type(GFP_KERNEL)][__kmalloc_index(size, false)];
/* /*
* Verify that various helpers return the right values * Verify that various helpers return the right values

7
mm/slab_common.c
View File

@ -754,8 +754,8 @@ struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
/* /*
* kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time. * kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time.
* kmalloc_index() supports up to 2^26=64MB, so the final entry of the table is * kmalloc_index() supports up to 2^25=32MB, so the final entry of the table is
* kmalloc-67108864. * kmalloc-32M.
*/ */
const struct kmalloc_info_struct kmalloc_info[] __initconst = { const struct kmalloc_info_struct kmalloc_info[] __initconst = {
INIT_KMALLOC_INFO(0, 0), INIT_KMALLOC_INFO(0, 0),
@ -783,8 +783,7 @@ const struct kmalloc_info_struct kmalloc_info[] __initconst = {
INIT_KMALLOC_INFO(4194304, 4M), INIT_KMALLOC_INFO(4194304, 4M),
INIT_KMALLOC_INFO(8388608, 8M), INIT_KMALLOC_INFO(8388608, 8M),
INIT_KMALLOC_INFO(16777216, 16M), INIT_KMALLOC_INFO(16777216, 16M),
INIT_KMALLOC_INFO(33554432, 32M), INIT_KMALLOC_INFO(33554432, 32M)
INIT_KMALLOC_INFO(67108864, 64M)
}; };
/* /*