The patch titled
Subject: lib/stackdepot: avoid to return 0 handle
has been added to the -mm tree. Its filename is
lib-stackdepot-avoid-to-return-0-handle.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/lib-stackdepot-avoid-to-return-0-handle.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/lib-stackdepot-avoid-to-return-0-handle.patch
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------------------------------------------------------
From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Subject: lib/stackdepot: avoid to return 0 handle
Recently, we allow to save the stacktrace whose hashed value is 0. It
causes the problem that stackdepot could return 0 even if in success.
User of stackdepot cannot distinguish whether it is success or not so we
need to solve this problem. In this patch, 1 bit are added to handle and
make valid handle none 0 by setting this bit. After that, valid handle
will not be 0 and 0 handle will represent failure correctly.
Fixes: 33334e25769c ("lib/stackdepot.c: allow the stack trace hash
to be zero")
Link: http://lkml.kernel.org/r/1462252403-1106-1-git-send-email-iamjoonsoo.kim@xxxxxxx
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/stackdepot.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff -puN lib/stackdepot.c~lib-stackdepot-avoid-to-return-0-handle lib/stackdepot.c
--- a/lib/stackdepot.c~lib-stackdepot-avoid-to-return-0-handle
+++ a/lib/stackdepot.c
@@ -42,12 +42,14 @@
#define DEPOT_STACK_BITS (sizeof(depot_stack_handle_t) * 8)
+#define STACK_ALLOC_NULL_PROTECTION_BITS 1
#define STACK_ALLOC_ORDER 2 /* 'Slab' size order for stack depot, 4 pages */
#define STACK_ALLOC_SIZE (1LL << (PAGE_SHIFT + STACK_ALLOC_ORDER))
#define STACK_ALLOC_ALIGN 4
#define STACK_ALLOC_OFFSET_BITS (STACK_ALLOC_ORDER + PAGE_SHIFT - \
STACK_ALLOC_ALIGN)
-#define STACK_ALLOC_INDEX_BITS (DEPOT_STACK_BITS - STACK_ALLOC_OFFSET_BITS)
+#define STACK_ALLOC_INDEX_BITS (DEPOT_STACK_BITS - \
+ STACK_ALLOC_NULL_PROTECTION_BITS - STACK_ALLOC_OFFSET_BITS)
#define STACK_ALLOC_SLABS_CAP 1024
#define STACK_ALLOC_MAX_SLABS \
(((1LL << (STACK_ALLOC_INDEX_BITS)) < STACK_ALLOC_SLABS_CAP) ? \
@@ -59,6 +61,7 @@ union handle_parts {
struct {
u32 slabindex : STACK_ALLOC_INDEX_BITS;
u32 offset : STACK_ALLOC_OFFSET_BITS;
+ u32 valid : STACK_ALLOC_NULL_PROTECTION_BITS;
};
};
@@ -136,6 +139,7 @@ static struct stack_record *depot_alloc_
stack->size = size;
stack->handle.slabindex = depot_index;
stack->handle.offset = depot_offset >> STACK_ALLOC_ALIGN;
+ stack->handle.valid = 1;
memcpy(stack->entries, entries, size * sizeof(unsigned long));
depot_offset += required_size;
_
Patches currently in -mm which might be from iamjoonsoo.kim@xxxxxxx are
lib-stackdepot-avoid-to-return-0-handle.patch
mm-slab-fix-the-theoretical-race-by-holding-proper-lock.patch
mm-slab-remove-bad_alien_magic-again.patch
mm-slab-drain-the-free-slab-as-much-as-possible.patch
mm-slab-factor-out-kmem_cache_node-initialization-code.patch
mm-slab-factor-out-kmem_cache_node-initialization-code-fix.patch
mm-slab-clean-up-kmem_cache_node-setup.patch
mm-slab-dont-keep-free-slabs-if-free_objects-exceeds-free_limit.patch
mm-slab-racy-access-modify-the-slab-color.patch
mm-slab-make-cache_grow-handle-the-page-allocated-on-arbitrary-node.patch
mm-slab-separate-cache_grow-to-two-parts.patch
mm-slab-refill-cpu-cache-through-a-new-slab-without-holding-a-node-lock.patch
mm-slab-lockless-decision-to-grow-cache.patch
mm-page_ref-use-page_ref-helper-instead-of-direct-modification-of-_count.patch
mm-rename-_count-field-of-the-struct-page-to-_refcount.patch
mm-rename-_count-field-of-the-struct-page-to-_refcount-fix-fix-fix.patch
mm-hugetlb-add-same-zone-check-in-pfn_range_valid_gigantic.patch
mm-memory_hotplug-add-comment-to-some-functions-related-to-memory-hotplug.patch
mm-vmstat-add-zone-range-overlapping-check.patch
mm-page_owner-add-zone-range-overlapping-check.patch
power-add-zone-range-overlapping-check.patch
mm-writeback-correct-dirty-page-calculation-for-highmem.patch
mm-page_alloc-correct-highmem-memory-statistics.patch
mm-highmem-make-nr_free_highpages-handles-all-highmem-zones-by-itself.patch
mm-vmstat-make-node_page_state-handles-all-zones-by-itself.patch
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