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authorQian Cai <cai@lca.pw>2020-05-27 22:20:40 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-05-28 11:35:40 -0700
commitaf4798a5bba60af881626780cbc6457cb162bfd1 (patch)
tree058e5a720d0ad94920f9281bd26b88a207526f70
parent444fc5cde64330661bf59944c43844e7d4c2ccd8 (diff)
downloadlinux-sh-af4798a5bba60af881626780cbc6457cb162bfd1.tar.gz
mm/z3fold: silence kmemleak false positives of slots
Kmemleak reported many leaks while under memory pressue in, slots = alloc_slots(pool, gfp); which is referenced by "zhdr" in init_z3fold_page(), zhdr->slots = slots; However, "zhdr" could be gone without freeing slots as the later will be freed separately when the last "handle" off of "handles" array is freed. It will be within "slots" which is always aligned. unreferenced object 0xc000000fdadc1040 (size 104): comm "oom04", pid 140476, jiffies 4295359280 (age 3454.970s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: z3fold_zpool_malloc+0x7b0/0xe10 alloc_slots at mm/z3fold.c:214 (inlined by) init_z3fold_page at mm/z3fold.c:412 (inlined by) z3fold_alloc at mm/z3fold.c:1161 (inlined by) z3fold_zpool_malloc at mm/z3fold.c:1735 zpool_malloc+0x34/0x50 zswap_frontswap_store+0x60c/0xda0 zswap_frontswap_store at mm/zswap.c:1093 __frontswap_store+0x128/0x330 swap_writepage+0x58/0x110 pageout+0x16c/0xa40 shrink_page_list+0x1ac8/0x25c0 shrink_inactive_list+0x270/0x730 shrink_lruvec+0x444/0xf30 shrink_node+0x2a4/0x9c0 do_try_to_free_pages+0x158/0x640 try_to_free_pages+0x1bc/0x5f0 __alloc_pages_slowpath.constprop.60+0x4dc/0x15a0 __alloc_pages_nodemask+0x520/0x650 alloc_pages_vma+0xc0/0x420 handle_mm_fault+0x1174/0x1bf0 Signed-off-by: Qian Cai <cai@lca.pw> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Vitaly Wool <vitaly.wool@konsulko.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Link: http://lkml.kernel.org/r/20200522220052.2225-1-cai@lca.pw Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/z3fold.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/z3fold.c b/mm/z3fold.c
index 8c3bb5e508b8..460b0feced26 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -43,6 +43,7 @@
#include <linux/spinlock.h>
#include <linux/zpool.h>
#include <linux/magic.h>
+#include <linux/kmemleak.h>
/*
* NCHUNKS_ORDER determines the internal allocation granularity, effectively
@@ -215,6 +216,8 @@ static inline struct z3fold_buddy_slots *alloc_slots(struct z3fold_pool *pool,
(gfp & ~(__GFP_HIGHMEM | __GFP_MOVABLE)));
if (slots) {
+ /* It will be freed separately in free_handle(). */
+ kmemleak_not_leak(slots);
memset(slots->slot, 0, sizeof(slots->slot));
slots->pool = (unsigned long)pool;
rwlock_init(&slots->lock);