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authorVlastimil Babka <vbabka@suse.cz>2018-10-26 15:05:38 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-10-26 16:26:31 -0700
commit1291523f2c1d631fea34102fd241fb54a4e8f7a0 (patch)
treee7b12363e6e5b49f98692e8e4c585b0dcca33b5c /include/linux/slab.h
parentcc252eae85e09552f9c1e7ac0c3227f835efdf2d (diff)
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mm, slab/slub: introduce kmalloc-reclaimable caches
Kmem caches can be created with a SLAB_RECLAIM_ACCOUNT flag, which indicates they contain objects which can be reclaimed under memory pressure (typically through a shrinker). This makes the slab pages accounted as NR_SLAB_RECLAIMABLE in vmstat, which is reflected also the MemAvailable meminfo counter and in overcommit decisions. The slab pages are also allocated with __GFP_RECLAIMABLE, which is good for anti-fragmentation through grouping pages by mobility. The generic kmalloc-X caches are created without this flag, but sometimes are used also for objects that can be reclaimed, which due to varying size cannot have a dedicated kmem cache with SLAB_RECLAIM_ACCOUNT flag. A prominent example are dcache external names, which prompted the creation of a new, manually managed vmstat counter NR_INDIRECTLY_RECLAIMABLE_BYTES in commit f1782c9bc547 ("dcache: account external names as indirectly reclaimable memory"). To better handle this and any other similar cases, this patch introduces SLAB_RECLAIM_ACCOUNT variants of kmalloc caches, named kmalloc-rcl-X. They are used whenever the kmalloc() call passes __GFP_RECLAIMABLE among gfp flags. They are added to the kmalloc_caches array as a new type. Allocations with both __GFP_DMA and __GFP_RECLAIMABLE will use a dma type cache. This change only applies to SLAB and SLUB, not SLOB. This is fine, since SLOB's target are tiny system and this patch does add some overhead of kmem management objects. Link: http://lkml.kernel.org/r/20180731090649.16028-3-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Christoph Lameter <cl@linux.com> Acked-by: Roman Gushchin <guro@fb.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Laura Abbott <labbott@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: Vijayanand Jitta <vjitta@codeaurora.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/slab.h')
-rw-r--r--include/linux/slab.h16
1 files changed, 15 insertions, 1 deletions
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 2a7137043e91..918f374e7156 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -295,8 +295,13 @@ static inline void __check_heap_object(const void *ptr, unsigned long n,
#define SLAB_OBJ_MIN_SIZE (KMALLOC_MIN_SIZE < 16 ? \
(KMALLOC_MIN_SIZE) : 16)
+/*
+ * Whenever changing this, take care of that kmalloc_type() and
+ * create_kmalloc_caches() still work as intended.
+ */
enum kmalloc_cache_type {
KMALLOC_NORMAL = 0,
+ KMALLOC_RECLAIM,
#ifdef CONFIG_ZONE_DMA
KMALLOC_DMA,
#endif
@@ -310,12 +315,21 @@ kmalloc_caches[NR_KMALLOC_TYPES][KMALLOC_SHIFT_HIGH + 1];
static __always_inline enum kmalloc_cache_type kmalloc_type(gfp_t flags)
{
int is_dma = 0;
+ int type_dma = 0;
+ int is_reclaimable;
#ifdef CONFIG_ZONE_DMA
is_dma = !!(flags & __GFP_DMA);
+ type_dma = is_dma * KMALLOC_DMA;
#endif
- return is_dma;
+ is_reclaimable = !!(flags & __GFP_RECLAIMABLE);
+
+ /*
+ * If an allocation is both __GFP_DMA and __GFP_RECLAIMABLE, return
+ * KMALLOC_DMA and effectively ignore __GFP_RECLAIMABLE
+ */
+ return type_dma + (is_reclaimable & !is_dma) * KMALLOC_RECLAIM;
}
/*