From: Yu Zhao <yuzhao@google.com> To: Christoph Lameter <cl@linux.com>, Pekka Enberg <penberg@kernel.org>, David Rientjes <rientjes@google.com>, Joonsoo Kim <iamjoonsoo.kim@lge.com>, Andrew Morton <akpm@linux-foundation.org>, "Kirill A . Shutemov" <kirill@shutemov.name>, Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Yu Zhao <yuzhao@google.com> Subject: [PATCH 1/3] mm: correct mask size for slub page->objects Date: Wed, 11 Sep 2019 18:29:27 -0600 Message-ID: <20190912002929.78873-1-yuzhao@google.com> (raw) In-Reply-To: <20190911071331.770ecddff6a085330bf2b5f2@linux-foundation.org> Mask of slub objects per page shouldn't be larger than what page->objects can hold. It requires more than 2^15 objects to hit the problem, and I don't think anybody would. It'd be nice to have the mask fixed, but not really worth cc'ing the stable. Fixes: 50d5c41cd151 ("slub: Do not use frozen page flag but a bit in the page counters") Signed-off-by: Yu Zhao <yuzhao@google.com> --- mm/slub.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/mm/slub.c b/mm/slub.c index 8834563cdb4b..62053ceb4464 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -187,7 +187,7 @@ static inline bool kmem_cache_has_cpu_partial(struct kmem_cache *s) */ #define DEBUG_METADATA_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER) -#define OO_SHIFT 16 +#define OO_SHIFT 15 #define OO_MASK ((1 << OO_SHIFT) - 1) #define MAX_OBJS_PER_PAGE 32767 /* since page.objects is u15 */ @@ -343,6 +343,8 @@ static inline unsigned int oo_order(struct kmem_cache_order_objects x) static inline unsigned int oo_objects(struct kmem_cache_order_objects x) { + BUILD_BUG_ON(OO_MASK > MAX_OBJS_PER_PAGE); + return x.x & OO_MASK; } -- 2.23.0.162.g0b9fbb3734-goog
next prev parent reply index Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-09-09 6:10 [PATCH] mm: avoid slub allocation while holding list_lock Yu Zhao 2019-09-09 16:00 ` Kirill A. Shutemov [not found] ` <e5e25aa3-651d-92b4-ac82-c5011c66a7cb@I-love.SAKURA.ne.jp> 2019-09-09 21:39 ` Yu Zhao [not found] ` <201909100141.x8A1fVdu048305@www262.sakura.ne.jp> 2019-09-10 2:16 ` Yu Zhao 2019-09-10 9:16 ` Kirill A. Shutemov 2019-09-11 14:13 ` Andrew Morton 2019-09-12 0:29 ` Yu Zhao [this message] 2019-09-12 0:29 ` [PATCH 2/3] " Yu Zhao 2019-09-12 0:44 ` Kirill A. Shutemov 2019-09-12 1:31 ` Yu Zhao 2019-09-12 2:31 ` [PATCH v2 1/4] mm: correct mask size for slub page->objects Yu Zhao 2019-09-12 2:31 ` [PATCH v2 2/4] mm: clean up validate_slab() Yu Zhao 2019-09-12 9:46 ` Kirill A. Shutemov 2019-09-12 2:31 ` [PATCH v2 3/4] mm: avoid slub allocation while holding list_lock Yu Zhao 2019-09-12 10:04 ` Kirill A. Shutemov 2019-09-12 2:31 ` [PATCH v2 4/4] mm: lock slub page when listing objects Yu Zhao 2019-09-12 10:06 ` Kirill A. Shutemov 2019-09-12 21:12 ` Yu Zhao 2019-09-13 14:58 ` Christopher Lameter 2019-09-12 9:40 ` [PATCH v2 1/4] mm: correct mask size for slub page->objects Kirill A. Shutemov 2019-09-12 21:11 ` Yu Zhao 2019-09-12 22:03 ` Kirill A. Shutemov 2019-09-14 0:07 ` [PATCH v3 1/2] mm: clean up validate_slab() Yu Zhao 2019-09-14 0:07 ` [PATCH v3 2/2] mm: avoid slub allocation while holding list_lock Yu Zhao 2019-09-16 8:39 ` [PATCH v3 1/2] mm: clean up validate_slab() Kirill A. Shutemov 2019-11-08 19:39 ` [PATCH v4 " Yu Zhao 2019-11-08 19:39 ` [PATCH v4 2/2] mm: avoid slub allocation while holding list_lock Yu Zhao 2019-11-09 20:52 ` Christopher Lameter 2019-11-09 23:01 ` Yu Zhao 2019-11-09 23:16 ` Christopher Lameter 2019-11-10 18:47 ` Yu Zhao 2019-11-11 15:47 ` Christopher Lameter 2019-11-11 15:55 ` [FIX] slub: Remove kmalloc under list_lock from list_slab_objects() V2 Christopher Lameter 2019-11-30 23:09 ` Andrew Morton 2019-12-02 15:12 ` Christopher Lameter 2019-12-07 22:03 ` Yu Zhao 2020-01-10 14:11 ` Vlastimil Babka [not found] ` <e0ed44ae-8dae-e8db-9d14-2b09b239af8e@i-love.sakura.ne.jp> 2020-01-13 1:34 ` Christopher Lameter 2019-11-11 18:15 ` [PATCH v4 2/2] mm: avoid slub allocation while holding list_lock Shakeel Butt 2019-09-12 0:29 ` [PATCH 3/3] mm: lock slub page when listing objects Yu Zhao
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