From: Peter Collingbourne <pcc@google.com> To: catalin.marinas@arm.com, andreyknvl@gmail.com Cc: Peter Collingbourne <pcc@google.com>, linux-mm@kvack.org, kasan-dev@googlegroups.com, ryabinin.a.a@gmail.com, linux-arm-kernel@lists.infradead.org, vincenzo.frascino@arm.com, will@kernel.org, eugenis@google.com, stable@vger.kernel.org Subject: [PATCH] Revert "kasan: drop skip_kasan_poison variable in free_pages_prepare" Date: Thu, 23 Feb 2023 22:15:50 -0800 [thread overview] Message-ID: <20230224061550.177541-1-pcc@google.com> (raw) This reverts commit 487a32ec24be819e747af8c2ab0d5c515508086a. The should_skip_kasan_poison() function reads the PG_skip_kasan_poison flag from page->flags. However, this line of code in free_pages_prepare(): page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; clears most of page->flags, including PG_skip_kasan_poison, before calling should_skip_kasan_poison(), which meant that it would never return true as a result of the page flag being set. Therefore, fix the code to call should_skip_kasan_poison() before clearing the flags, as we were doing before the reverted patch. Signed-off-by: Peter Collingbourne <pcc@google.com> Fixes: 487a32ec24be ("kasan: drop skip_kasan_poison variable in free_pages_prepare") Cc: <stable@vger.kernel.org> # 6.1 Link: https://linux-review.googlesource.com/id/Ic4f13affeebd20548758438bb9ed9ca40e312b79 --- mm/page_alloc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ac1fc986af44..7136c36c5d01 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1398,6 +1398,7 @@ static __always_inline bool free_pages_prepare(struct page *page, unsigned int order, bool check_free, fpi_t fpi_flags) { int bad = 0; + bool skip_kasan_poison = should_skip_kasan_poison(page, fpi_flags); bool init = want_init_on_free(); VM_BUG_ON_PAGE(PageTail(page), page); @@ -1470,7 +1471,7 @@ static __always_inline bool free_pages_prepare(struct page *page, * With hardware tag-based KASAN, memory tags must be set before the * page becomes unavailable via debug_pagealloc or arch_free_page. */ - if (!should_skip_kasan_poison(page, fpi_flags)) { + if (!skip_kasan_poison) { kasan_poison_pages(page, order, init); /* Memory is already initialized if KASAN did it internally. */ -- 2.39.2.637.g21b0678d19-goog
WARNING: multiple messages have this Message-ID (diff)
From: Peter Collingbourne <pcc@google.com> To: catalin.marinas@arm.com, andreyknvl@gmail.com Cc: Peter Collingbourne <pcc@google.com>, linux-mm@kvack.org, kasan-dev@googlegroups.com, ryabinin.a.a@gmail.com, linux-arm-kernel@lists.infradead.org, vincenzo.frascino@arm.com, will@kernel.org, eugenis@google.com, stable@vger.kernel.org Subject: [PATCH] Revert "kasan: drop skip_kasan_poison variable in free_pages_prepare" Date: Thu, 23 Feb 2023 22:15:50 -0800 [thread overview] Message-ID: <20230224061550.177541-1-pcc@google.com> (raw) This reverts commit 487a32ec24be819e747af8c2ab0d5c515508086a. The should_skip_kasan_poison() function reads the PG_skip_kasan_poison flag from page->flags. However, this line of code in free_pages_prepare(): page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; clears most of page->flags, including PG_skip_kasan_poison, before calling should_skip_kasan_poison(), which meant that it would never return true as a result of the page flag being set. Therefore, fix the code to call should_skip_kasan_poison() before clearing the flags, as we were doing before the reverted patch. Signed-off-by: Peter Collingbourne <pcc@google.com> Fixes: 487a32ec24be ("kasan: drop skip_kasan_poison variable in free_pages_prepare") Cc: <stable@vger.kernel.org> # 6.1 Link: https://linux-review.googlesource.com/id/Ic4f13affeebd20548758438bb9ed9ca40e312b79 --- mm/page_alloc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ac1fc986af44..7136c36c5d01 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1398,6 +1398,7 @@ static __always_inline bool free_pages_prepare(struct page *page, unsigned int order, bool check_free, fpi_t fpi_flags) { int bad = 0; + bool skip_kasan_poison = should_skip_kasan_poison(page, fpi_flags); bool init = want_init_on_free(); VM_BUG_ON_PAGE(PageTail(page), page); @@ -1470,7 +1471,7 @@ static __always_inline bool free_pages_prepare(struct page *page, * With hardware tag-based KASAN, memory tags must be set before the * page becomes unavailable via debug_pagealloc or arch_free_page. */ - if (!should_skip_kasan_poison(page, fpi_flags)) { + if (!skip_kasan_poison) { kasan_poison_pages(page, order, init); /* Memory is already initialized if KASAN did it internally. */ -- 2.39.2.637.g21b0678d19-goog _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next reply other threads:[~2023-02-24 6:16 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-02-24 6:15 Peter Collingbourne [this message] 2023-02-24 6:15 ` [PATCH] Revert "kasan: drop skip_kasan_poison variable in free_pages_prepare" Peter Collingbourne 2023-02-27 0:16 ` Andrey Konovalov 2023-02-27 0:16 ` Andrey Konovalov
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