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Mon, 7 Apr 2025 14:02:05 +0000 (UTC) Received: from hydra.redhat.com (unknown [10.45.225.175]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 4EDB6192C7C3; Mon, 7 Apr 2025 14:02:00 +0000 (UTC) From: Jocelyn Falempe To: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Ryosuke Yasuoka , Javier Martinez Canillas , Wei Yang , Andrew Morton , David Hildenbrand , John Ogness , Thomas Gleixner , linux-mm@kvack.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Cc: Jocelyn Falempe , Simona Vetter Subject: [PATCH v3 1/2] mm/kmap: Add kmap_local_page_try_from_panic() Date: Mon, 7 Apr 2025 15:42:25 +0200 Message-ID: <20250407140138.162383-2-jfalempe@redhat.com> In-Reply-To: <20250407140138.162383-1-jfalempe@redhat.com> References: <20250407140138.162383-1-jfalempe@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 077C34000F X-Stat-Signature: kqft7bwr1c4eetqbzwi3tmpzrhtgd9uz X-HE-Tag: 1744034539-540372 X-HE-Meta: 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 AM8lx+c0 W2sbfY37Tn06qr5xlIqD5/dCjwGbU/rAnVpG5gtX5pUqAhS/gzOhPNTUaCrx8citv0++3LA9tilaeHe9fU8bwi5hTOJUWVd7iL6Bsu3B9ymYFLGx1dAlWfsFTd8078dr1J9IOU+XF5T/7Htx7pANAPrhlcTdL6HtTaSYmPkHXkdb52tu7yhNPr8Uw/w== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: kmap_local_page() can be unsafe to call from a panic handler, if CONFIG_HIGHMEM is set, and the page is in the highmem zone. So add kmap_local_page_try_from_panic() to handle this case. Suggested-by: Simona Vetter Reviewed-by: Thomas Gleixner Signed-off-by: Jocelyn Falempe --- v3: * Add a comment in kmap_local_page_try_from_panic() (Thomas Gleixner) include/linux/highmem-internal.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/include/linux/highmem-internal.h b/include/linux/highmem-internal.h index dd100e849f5e0..9a7683d79a4b1 100644 --- a/include/linux/highmem-internal.h +++ b/include/linux/highmem-internal.h @@ -73,6 +73,14 @@ static inline void *kmap_local_page(struct page *page) return __kmap_local_page_prot(page, kmap_prot); } +static inline void *kmap_local_page_try_from_panic(struct page *page) +{ + if (!PageHighMem(page)) + return page_address(page); + /* If the page is in HighMem, it's not safe to kmap it.*/ + return NULL; +} + static inline void *kmap_local_folio(struct folio *folio, size_t offset) { struct page *page = folio_page(folio, offset / PAGE_SIZE); @@ -180,6 +188,11 @@ static inline void *kmap_local_page(struct page *page) return page_address(page); } +static inline void *kmap_local_page_try_from_panic(struct page *page) +{ + return page_address(page); +} + static inline void *kmap_local_folio(struct folio *folio, size_t offset) { return page_address(&folio->page) + offset;