From: Andrew Morton <akpm@linux-foundation.org>
To: akpm@linux-foundation.org, dvyukov@google.com, elver@google.com,
glider@google.com, gregkh@linuxfoundation.org,
linux-mm@kvack.org, mm-commits@vger.kernel.org,
stable@vger.kernel.org, torvalds@linux-foundation.org
Subject: [patch 04/15] kfence: move the size check to the beginning of __kfence_alloc()
Date: Fri, 23 Jul 2021 15:50:11 -0700 [thread overview]
Message-ID: <20210723225011.pURAgvl2s%akpm@linux-foundation.org> (raw)
In-Reply-To: <20210723154926.c6cda0f262b1990b950a5886@linux-foundation.org>
From: Alexander Potapenko <glider@google.com>
Subject: kfence: move the size check to the beginning of __kfence_alloc()
Check the allocation size before toggling kfence_allocation_gate. This
way allocations that can't be served by KFENCE will not result in waiting
for another CONFIG_KFENCE_SAMPLE_INTERVAL without allocating anything.
Link: https://lkml.kernel.org/r/20210714092222.1890268-1-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Suggested-by: Marco Elver <elver@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: <stable@vger.kernel.org> [5.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/kfence/core.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
--- a/mm/kfence/core.c~kfence-move-the-size-check-to-the-beginning-of-__kfence_alloc
+++ a/mm/kfence/core.c
@@ -734,6 +734,13 @@ void kfence_shutdown_cache(struct kmem_c
void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags)
{
/*
+ * Perform size check before switching kfence_allocation_gate, so that
+ * we don't disable KFENCE without making an allocation.
+ */
+ if (size > PAGE_SIZE)
+ return NULL;
+
+ /*
* allocation_gate only needs to become non-zero, so it doesn't make
* sense to continue writing to it and pay the associated contention
* cost, in case we have a large number of concurrent allocations.
@@ -757,9 +764,6 @@ void *__kfence_alloc(struct kmem_cache *
if (!READ_ONCE(kfence_enabled))
return NULL;
- if (size > PAGE_SIZE)
- return NULL;
-
return kfence_guarded_alloc(s, size, flags);
}
_
next prev parent reply other threads:[~2021-07-23 22:50 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-23 22:49 incoming Andrew Morton
2021-07-23 22:50 ` [patch 01/15] userfaultfd: do not untag user pointers Andrew Morton
2021-07-23 22:50 ` [patch 02/15] selftest: use mmap instead of posix_memalign to allocate memory Andrew Morton
2021-07-23 22:50 ` [patch 03/15] kfence: defer kfence_test_init to ensure that kunit debugfs is created Andrew Morton
2021-07-23 22:50 ` Andrew Morton [this message]
2021-07-23 22:50 ` [patch 05/15] kfence: skip all GFP_ZONEMASK allocations Andrew Morton
2021-07-23 22:50 ` [patch 06/15] mm: call flush_dcache_page() in memcpy_to_page() and memzero_page() Andrew Morton
2021-07-24 6:59 ` Christoph Hellwig
2021-07-24 16:23 ` Matthew Wilcox
2021-07-23 22:50 ` [patch 07/15] mm: use kmap_local_page in memzero_page Andrew Morton
2021-07-23 22:50 ` [patch 08/15] mm: page_alloc: fix page_poison=1 / INIT_ON_ALLOC_DEFAULT_ON interaction Andrew Morton
2021-07-23 22:50 ` [patch 09/15] memblock: make for_each_mem_range() traverse MEMBLOCK_HOTPLUG regions Andrew Morton
2021-07-23 22:50 ` [patch 10/15] writeback, cgroup: remove wb from offline list before releasing refcnt Andrew Morton
2021-07-23 22:50 ` [patch 11/15] writeback, cgroup: do not reparent dax inodes Andrew Morton
2021-07-23 22:50 ` [patch 12/15] mm/secretmem: wire up ->set_page_dirty Andrew Morton
2021-07-23 22:50 ` [patch 13/15] mm: mmap_lock: fix disabling preemption directly Andrew Morton
2021-07-23 22:50 ` [patch 14/15] mm: fix the deadlock in finish_fault() Andrew Morton
2021-07-23 22:50 ` [patch 15/15] hugetlbfs: fix mount mode command line processing Andrew Morton
2021-07-24 1:41 ` Al Viro
2021-07-26 5:22 ` Andrew Morton
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