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authorAlexander Potapenko <glider@google.com>2022-09-05 14:24:27 +0200
committerAndrew Morton <akpm@linux-foundation.org>2022-10-12 18:51:48 -0700
commitac801e7e252c5588325e3c983c7d4167fc68c024 (patch)
tree480872f2331445b10d709f14dea7a7f99dd24b31 /mm
parent4fa0e3ff217f775cb58d2d6d51820ec519243fb9 (diff)
kmsan: unpoison @tlb in arch_tlb_gather_mmu()
This is an optimization to reduce stackdepot pressure. struct mmu_gather contains 7 1-bit fields packed into a 32-bit unsigned int value. The remaining 25 bits remain uninitialized and are never used, but KMSAN updates the origin for them in zap_pXX_range() in mm/memory.c, thus creating very long origin chains. This is technically correct, but consumes too much memory. Unpoisoning the whole structure will prevent creating such chains. Link: https://lkml.kernel.org/r/20220905122452.2258262-20-glider@google.com Signed-off-by: Alexander Potapenko <glider@google.com> Acked-by: Marco Elver <elver@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Eric Biggers <ebiggers@google.com> Cc: Eric Dumazet <edumazet@google.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Ilya Leoshkevich <iii@linux.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kees Cook <keescook@chromium.org> Cc: Liu Shixin <liushixin2@huawei.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vegard Nossum <vegard.nossum@oracle.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/mmu_gather.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/mm/mmu_gather.c b/mm/mmu_gather.c
index a71924bd38c0..add4244e5790 100644
--- a/mm/mmu_gather.c
+++ b/mm/mmu_gather.c
@@ -1,6 +1,7 @@
#include <linux/gfp.h>
#include <linux/highmem.h>
#include <linux/kernel.h>
+#include <linux/kmsan-checks.h>
#include <linux/mmdebug.h>
#include <linux/mm_types.h>
#include <linux/mm_inline.h>
@@ -265,6 +266,15 @@ void tlb_flush_mmu(struct mmu_gather *tlb)
static void __tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
bool fullmm)
{
+ /*
+ * struct mmu_gather contains 7 1-bit fields packed into a 32-bit
+ * unsigned int value. The remaining 25 bits remain uninitialized
+ * and are never used, but KMSAN updates the origin for them in
+ * zap_pXX_range() in mm/memory.c, thus creating very long origin
+ * chains. This is technically correct, but consumes too much memory.
+ * Unpoisoning the whole structure will prevent creating such chains.
+ */
+ kmsan_unpoison_memory(tlb, sizeof(*tlb));
tlb->mm = mm;
tlb->fullmm = fullmm;