The patch titled
Subject: kfence: count unexpectedly skipped allocations
has been added to the -mm tree. Its filename is
kfence-count-unexpectedly-skipped-allocations.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/kfence-count-unexpectedly-skipped-allocations.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/kfence-count-unexpectedly-skipped-allocations.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Marco Elver <elver@xxxxxxxxxx>
Subject: kfence: count unexpectedly skipped allocations
Maintain a counter to count allocations that are skipped due to being
incompatible (oversized, incompatible gfp flags) or no capacity.
This is to compute the fraction of allocations that could not be serviced
by KFENCE, which we expect to be rare.
Link: https://lkml.kernel.org/r/20210923104803.2620285-2-elver@xxxxxxxxxx
Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
Reviewed-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Acked-by: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Aleksandr Nogikh <nogikh@xxxxxxxxxx>
Cc: Jann Horn <jannh@xxxxxxxxxx>
Cc: Taras Madan <tarasmadan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/kfence/core.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
--- a/mm/kfence/core.c~kfence-count-unexpectedly-skipped-allocations
+++ a/mm/kfence/core.c
@@ -112,6 +112,8 @@ enum kfence_counter_id {
KFENCE_COUNTER_FREES,
KFENCE_COUNTER_ZOMBIES,
KFENCE_COUNTER_BUGS,
+ KFENCE_COUNTER_SKIP_INCOMPAT,
+ KFENCE_COUNTER_SKIP_CAPACITY,
KFENCE_COUNTER_COUNT,
};
static atomic_long_t counters[KFENCE_COUNTER_COUNT];
@@ -121,6 +123,8 @@ static const char *const counter_names[]
[KFENCE_COUNTER_FREES] = "total frees",
[KFENCE_COUNTER_ZOMBIES] = "zombie allocations",
[KFENCE_COUNTER_BUGS] = "total bugs",
+ [KFENCE_COUNTER_SKIP_INCOMPAT] = "skipped allocations (incompatible)",
+ [KFENCE_COUNTER_SKIP_CAPACITY] = "skipped allocations (capacity)",
};
static_assert(ARRAY_SIZE(counter_names) == KFENCE_COUNTER_COUNT);
@@ -271,8 +275,10 @@ static void *kfence_guarded_alloc(struct
list_del_init(&meta->list);
}
raw_spin_unlock_irqrestore(&kfence_freelist_lock, flags);
- if (!meta)
+ if (!meta) {
+ atomic_long_inc(&counters[KFENCE_COUNTER_SKIP_CAPACITY]);
return NULL;
+ }
if (unlikely(!raw_spin_trylock_irqsave(&meta->lock, flags))) {
/*
@@ -740,8 +746,10 @@ void *__kfence_alloc(struct kmem_cache *
* Perform size check before switching kfence_allocation_gate, so that
* we don't disable KFENCE without making an allocation.
*/
- if (size > PAGE_SIZE)
+ if (size > PAGE_SIZE) {
+ atomic_long_inc(&counters[KFENCE_COUNTER_SKIP_INCOMPAT]);
return NULL;
+ }
/*
* Skip allocations from non-default zones, including DMA. We cannot
@@ -749,8 +757,10 @@ void *__kfence_alloc(struct kmem_cache *
* properties (e.g. reside in DMAable memory).
*/
if ((flags & GFP_ZONEMASK) ||
- (s->flags & (SLAB_CACHE_DMA | SLAB_CACHE_DMA32)))
+ (s->flags & (SLAB_CACHE_DMA | SLAB_CACHE_DMA32))) {
+ atomic_long_inc(&counters[KFENCE_COUNTER_SKIP_INCOMPAT]);
return NULL;
+ }
/*
* allocation_gate only needs to become non-zero, so it doesn't make
_
Patches currently in -mm which might be from elver@xxxxxxxxxx are
kasan-fix-kconfig-check-of-cc_has_working_nosanitize_address.patch
lib-stackdepot-include-gfph.patch
lib-stackdepot-remove-unused-function-argument.patch
lib-stackdepot-introduce-__stack_depot_save.patch
kasan-common-provide-can_alloc-in-kasan_save_stack.patch
kasan-generic-introduce-kasan_record_aux_stack_noalloc.patch
workqueue-kasan-avoid-alloc_pages-when-recording-stack.patch
mm-fix-data-race-in-pagepoisoned.patch
stacktrace-move-filter_irq_stacks-to-kernel-stacktracec.patch
kfence-count-unexpectedly-skipped-allocations.patch
kfence-move-saving-stack-trace-of-allocations-into-__kfence_alloc.patch
kfence-limit-currently-covered-allocations-when-pool-nearly-full.patch
kfence-add-note-to-documentation-about-skipping-covered-allocations.patch
