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Mon, 22 Jun 2020 18:58:53 -0700 Received: by devvm1291.vll0.facebook.com (Postfix, from userid 111017) id 4DC3326DD020; Mon, 22 Jun 2020 18:58:48 -0700 (PDT) Smtp-Origin-Hostprefix: devvm From: Roman Gushchin Smtp-Origin-Hostname: devvm1291.vll0.facebook.com To: Andrew Morton , Christoph Lameter CC: Johannes Weiner , Michal Hocko , Shakeel Butt , , Vlastimil Babka , , , Roman Gushchin Smtp-Origin-Cluster: vll0c01 Subject: [PATCH v7 04/19] mm: slub: implement SLUB version of obj_to_index() Date: Mon, 22 Jun 2020 18:58:31 -0700 Message-ID: <20200623015846.1141975-5-guro@fb.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200623015846.1141975-1-guro@fb.com> References: <20200623015846.1141975-1-guro@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216,18.0.687 definitions=2020-06-22_16:2020-06-22,2020-06-22 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 impostorscore=0 phishscore=0 mlxscore=0 cotscore=-2147483648 suspectscore=2 adultscore=0 bulkscore=0 priorityscore=1501 lowpriorityscore=0 malwarescore=0 mlxlogscore=952 clxscore=1015 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006230012 X-FB-Internal: deliver X-Rspamd-Queue-Id: 459771801D30B X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: This commit implements SLUB version of the obj_to_index() function, which will be required to calculate the offset of obj_cgroup in the obj_cgroups vector to store/obtain the objcg ownership data. To make it faster, let's repeat the SLAB's trick introduced by commit 6a2d7a955d8d ("SLAB: use a multiply instead of a divide in obj_to_index()") and avoid an expensive division. Vlastimil Babka noticed, that SLUB does have already a similar function called slab_index(), which is defined only if SLUB_DEBUG is enabled. The function does a similar math, but with a division, and it also takes a page address instead of a page pointer. Let's remove slab_index() and replace it with the new helper __obj_to_index(), which takes a page address. obj_to_index() will be a simple wrapper taking a page pointer and passing page_address(page) into __obj_to_index(). Signed-off-by: Roman Gushchin Reviewed-by: Vlastimil Babka Acked-by: Johannes Weiner Reviewed-by: Shakeel Butt --- include/linux/slub_def.h | 16 ++++++++++++++++ mm/slub.c | 15 +++++---------- 2 files changed, 21 insertions(+), 10 deletions(-) diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h index d2153789bd9f..30e91c83d401 100644 --- a/include/linux/slub_def.h +++ b/include/linux/slub_def.h @@ -8,6 +8,7 @@ * (C) 2007 SGI, Christoph Lameter */ #include +#include enum stat_item { ALLOC_FASTPATH, /* Allocation from cpu slab */ @@ -86,6 +87,7 @@ struct kmem_cache { unsigned long min_partial; unsigned int size; /* The size of an object including metadata */ unsigned int object_size;/* The size of an object without metadata */ + struct reciprocal_value reciprocal_size; unsigned int offset; /* Free pointer offset */ #ifdef CONFIG_SLUB_CPU_PARTIAL /* Number of per cpu partial objects to keep around */ @@ -182,4 +184,18 @@ static inline void *nearest_obj(struct kmem_cache *cache, struct page *page, return result; } +/* Determine object index from a given position */ +static inline unsigned int __obj_to_index(const struct kmem_cache *cache, + void *addr, void *obj) +{ + return reciprocal_divide(kasan_reset_tag(obj) - addr, + cache->reciprocal_size); +} + +static inline unsigned int obj_to_index(const struct kmem_cache *cache, + const struct page *page, void *obj) +{ + return __obj_to_index(cache, page_address(page), obj); +} + #endif /* _LINUX_SLUB_DEF_H */ diff --git a/mm/slub.c b/mm/slub.c index c79d33cbe815..aa8d18824e62 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -317,12 +317,6 @@ static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp) __p < (__addr) + (__objects) * (__s)->size; \ __p += (__s)->size) -/* Determine object index from a given position */ -static inline unsigned int slab_index(void *p, struct kmem_cache *s, void *addr) -{ - return (kasan_reset_tag(p) - addr) / s->size; -} - static inline unsigned int order_objects(unsigned int order, unsigned int size) { return ((unsigned int)PAGE_SIZE << order) / size; @@ -465,7 +459,7 @@ static unsigned long *get_map(struct kmem_cache *s, struct page *page) bitmap_zero(object_map, page->objects); for (p = page->freelist; p; p = get_freepointer(s, p)) - set_bit(slab_index(p, s, addr), object_map); + set_bit(__obj_to_index(s, addr, p), object_map); return object_map; } @@ -3758,6 +3752,7 @@ static int calculate_sizes(struct kmem_cache *s, int forced_order) */ size = ALIGN(size, s->align); s->size = size; + s->reciprocal_size = reciprocal_value(size); if (forced_order >= 0) order = forced_order; else @@ -3862,7 +3857,7 @@ static void list_slab_objects(struct kmem_cache *s, struct page *page, map = get_map(s, page); for_each_object(p, s, addr, page->objects) { - if (!test_bit(slab_index(p, s, addr), map)) { + if (!test_bit(__obj_to_index(s, addr, p), map)) { pr_err("INFO: Object 0x%p @offset=%tu\n", p, p - addr); print_tracking(s, p); } @@ -4578,7 +4573,7 @@ static void validate_slab(struct kmem_cache *s, struct page *page) /* Now we know that a valid freelist exists */ map = get_map(s, page); for_each_object(p, s, addr, page->objects) { - u8 val = test_bit(slab_index(p, s, addr), map) ? + u8 val = test_bit(__obj_to_index(s, addr, p), map) ? SLUB_RED_INACTIVE : SLUB_RED_ACTIVE; if (!check_object(s, page, p, val)) @@ -4769,7 +4764,7 @@ static void process_slab(struct loc_track *t, struct kmem_cache *s, map = get_map(s, page); for_each_object(p, s, addr, page->objects) - if (!test_bit(slab_index(p, s, addr), map)) + if (!test_bit(__obj_to_index(s, addr, p), map)) add_location(t, s, get_track(s, p, alloc)); put_map(map); }