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De Francesco" To: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: "Fabio M. De Francesco" , Ira Weiny Subject: [PATCH] mm/page_poison: Replace kmap_atomic() with kmap_local_page() Date: Mon, 20 Nov 2023 15:28:23 +0100 Message-ID: <20231120142836.7219-1-fabio.maria.de.francesco@linux.intel.com> X-Mailer: git-send-email 2.42.0 MIME-Version: 1.0 X-Rspamd-Queue-Id: B25128001C X-Rspam-User: X-Stat-Signature: 663rn6iowtma39sns4p9t51nj16zoro8 X-Rspamd-Server: rspam03 X-HE-Tag: 1700490524-78971 X-HE-Meta: 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 30P3B6Vw r5jI8PDDG/dmE45fQBAMv5UNmJYBQfIarwkGhjBpIFLrG9/lRAcqZWJjy7o/WWrZlPUjKNtLBZeAn1+eY4bVMFXMMNUrwgoF6NnFlmLE/4fwcjLvdsrivSYTkB/5ldq3lPAEdZYUSsmItsOtIk5T03YuKa3e+ynQM4+3uyAjVuhMyuGuhVZ1rzQbIug== 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_atomic() has been deprecated in favor of kmap_local_page(). Therefore, replace kmap_atomic() with kmap_local_page(). kmap_atomic() is implemented like a kmap_local_page() which also disables page-faults and preemption (the latter only in !PREEMPT_RT kernels). The kernel virtual addresses returned by these two API are only valid in the context of the callers (i.e., they cannot be handed to other threads). With kmap_local_page() the mappings are per thread and CPU local like in kmap_atomic(); however, they can handle page-faults and can be called from any context (including interrupts). The tasks that call kmap_local_page() can be preempted and, when they are scheduled to run again, the kernel virtual addresses are restored and are still valid. The code blocks between the mappings and un-mappings do not rely on the above-mentioned side effects of kmap_atomic(), so that mere replacements of the old API with the new one is all that they require (i.e., there is no need to explicitly call pagefault_disable() and/or preempt_disable()). Cc: Ira Weiny Signed-off-by: Fabio M. De Francesco --- mm/page_poison.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/mm/page_poison.c b/mm/page_poison.c index b4f456437b7e..3e9037363cf9 100644 --- a/mm/page_poison.c +++ b/mm/page_poison.c @@ -21,13 +21,13 @@ early_param("page_poison", early_page_poison_param); static void poison_page(struct page *page) { - void *addr = kmap_atomic(page); + void *addr = kmap_local_page(page); /* KASAN still think the page is in-use, so skip it. */ kasan_disable_current(); memset(kasan_reset_tag(addr), PAGE_POISON, PAGE_SIZE); kasan_enable_current(); - kunmap_atomic(addr); + kunmap_local(addr); } void __kernel_poison_pages(struct page *page, int n) @@ -77,7 +77,7 @@ static void unpoison_page(struct page *page) { void *addr; - addr = kmap_atomic(page); + addr = kmap_local_page(page); kasan_disable_current(); /* * Page poisoning when enabled poisons each and every page @@ -86,7 +86,7 @@ static void unpoison_page(struct page *page) */ check_poison_mem(page, kasan_reset_tag(addr), PAGE_SIZE); kasan_enable_current(); - kunmap_atomic(addr); + kunmap_local(addr); } void __kernel_unpoison_pages(struct page *page, int n)