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h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CE69JfQIYQBEbu15G/3hwUd6A94Vi6U3OZgYwEH3fIYGXOB6hXHTmAVZn517eNaQt 0azC9G0CuuL874A8WC3Kuk3SB1PLbFN9Nd41oo/Xc3QKCJU0pPNtp+o2wngGg93l1c N1LhWHOd7Z/DT787YvXTGTmcgY8n8OtAJ50VR88U= From: Dev Jain To: akpm@linux-foundation.org, vbabka@kernel.org, harry@kernel.org, ryabinin.a.a@gmail.com Cc: Dev Jain , surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, hao.li@linux.dev, cl@gentwo.org, rientjes@google.com, roman.gushchin@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, glider@google.com, andreyknvl@gmail.com, dvyukov@google.com, vincenzo.frascino@arm.com, kasan-dev@googlegroups.com, ryan.roberts@arm.com, anshuman.khandual@arm.com, catalin.marinas@arm.com Subject: [PATCH 3/3] vmalloc: hw_tags: optimize vmalloc redzoning Date: Wed, 13 May 2026 16:27:34 +0530 Message-Id: <20260513105734.3380544-4-dev.jain@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260513105734.3380544-1-dev.jain@arm.com> References: <20260513105734.3380544-1-dev.jain@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: CBD0C14000D X-Rspamd-Server: rspam06 X-Stat-Signature: eodu843rsfcxbtdm51mrgg71gwrrpyzt X-HE-Tag: 1778669901-401287 X-HE-Meta: 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 IzO/MwQ5 jgI1MGshAluxQNT8nzQriJhkPDtqkEb2X4l0TL7JzOlZQyVD7zvd7GO6dYM3XM7N+MdB5nxyeI1Jr9yBySp47jIFyEvkSh041AM7Vo38/mYPIZd9EVIrK6zklrXYdtDHTTUbu3x6noKVkiVA5usoKTc+fclKOfYO6wDZ5JpKVJPbFI5B8lNsxcPhKNnGSmQIN9XWqss5UU7uv14aywKiqLm0qAHR6r3Fzij6vgMAHgpBp4nzXhTWM4Zx5iLGiEhA4uaj36EwSLJ34n20DTRchyiFO9/XhOxz2ylsMt75AEEWb7bSDfG2x/fWPv3NeUGiun0WgVkf6m0Al4lfKGbosgocrT1oO1+c0GykXGOGbBz77tPM= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: If the allocation size is less than a page, vmalloc first unpoisons the entire page, then poisons the tail with KASAN_TAG_INVALID (for hw tags), to catch OOB. Instead, unpoison the allocation length, and then poison the tail, saving some work. Signed-off-by: Dev Jain --- mm/kasan/hw_tags.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c index cbef5e450954..7c94f71b5f12 100644 --- a/mm/kasan/hw_tags.c +++ b/mm/kasan/hw_tags.c @@ -364,9 +364,6 @@ void *__kasan_unpoison_vmalloc(const void *start, unsigned long size, tag = (flags & KASAN_VMALLOC_KEEP_TAG) ? get_tag(start) : kasan_random_tag(); start = set_tag(start, tag); - /* Unpoison and initialize memory up to size. */ - kasan_unpoison(start, size, flags & KASAN_VMALLOC_INIT); - /* * Explicitly poison and initialize the in-page vmalloc() redzone. * Unlike software KASAN modes, hardware tag-based KASAN doesn't @@ -375,8 +372,14 @@ void *__kasan_unpoison_vmalloc(const void *start, unsigned long size, redzone_start = round_up((unsigned long)start + size, KASAN_GRANULE_SIZE); redzone_size = round_up(redzone_start, PAGE_SIZE) - redzone_start; - kasan_poison((void *)redzone_start, redzone_size, KASAN_TAG_INVALID, - flags & KASAN_VMALLOC_INIT); + + /* Unpoison and initialize memory before the redzone. */ + kasan_unpoison(start, redzone_start - (unsigned long)start, + flags & KASAN_VMALLOC_INIT); + + if (redzone_size) + kasan_poison((void *)redzone_start, redzone_size, + KASAN_TAG_INVALID, flags & KASAN_VMALLOC_INIT); /* * Set per-page tag flags to allow accessing physical memory for the -- 2.43.0