[PATCH AUTOSEL 5.19 12/58] mm: kasan: Skip page unpoisoning only if __GFP_SKIP_KASAN_UNPOISON

Sasha Levin
2022-08-08T01:32:53Z

From: Catalin Marinas <catalin.marinas@arm.com>

[ Upstream commit 6d05141a393071e104bf5be5ad4d0c79c6dff343 ]

Currently post_alloc_hook() skips the kasan unpoisoning if the tags will
be zeroed (__GFP_ZEROTAGS) or __GFP_SKIP_KASAN_UNPOISON is passed. Since
__GFP_ZEROTAGS is now accompanied by __GFP_SKIP_KASAN_UNPOISON, remove
the extra check.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20220610152141.2148929-4-catalin.marinas@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
mm/page_alloc.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 4d5c30dc757f..b0bcab50f0a3 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2361,7 +2361,7 @@ static inline bool check_new_pcp(struct page *page, unsigned int order)
}
#endif /* CONFIG_DEBUG_VM */

-static inline bool should_skip_kasan_unpoison(gfp_t flags, bool init_tags)
+static inline bool should_skip_kasan_unpoison(gfp_t flags)
{
/* Don't skip if a software KASAN mode is enabled. */
if (IS_ENABLED(CONFIG_KASAN_GENERIC) ||
@@ -2373,12 +2373,10 @@ static inline bool should_skip_kasan_unpoison(gfp_t flags, bool init_tags)
return true;

/*
- * With hardware tag-based KASAN enabled, skip if either:
- *
- * 1. Memory tags have already been cleared via tag_clear_highpage().
- * 2. Skipping has been requested via __GFP_SKIP_KASAN_UNPOISON.
+ * With hardware tag-based KASAN enabled, skip if this has been
+ * requested via __GFP_SKIP_KASAN_UNPOISON.
*/
- return init_tags || (flags & __GFP_SKIP_KASAN_UNPOISON);
+ return flags & __GFP_SKIP_KASAN_UNPOISON;
}

static inline bool should_skip_init(gfp_t flags)
@@ -2430,7 +2428,7 @@ inline void post_alloc_hook(struct page *page, unsigned int order,
/* Note that memory is already initialized by the loop above. */
init = false;
}
- if (!should_skip_kasan_unpoison(gfp_flags, init_tags)) {
+ if (!should_skip_kasan_unpoison(gfp_flags)) {
/* Unpoison shadow memory or set memory tags. */
kasan_unpoison_pages(page, order, init);

--
2.35.1