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Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1uFFYW-0000000CahR-2bDZ; Wed, 14 May 2025 17:06:08 +0000 From: "Matthew Wilcox (Oracle)" To: Andrew Morton Cc: "Matthew Wilcox (Oracle)" , ntfs3@lists.linux.dev, linux-mm@kvack.org, Alexander Viro , linux-fsdevel@vger.kernel.org, Hugh Dickins , stable@vger.kernel.org Subject: [PATCH 1/3] highmem: Add folio_test_partial_kmap() Date: Wed, 14 May 2025 18:06:02 +0100 Message-ID: <20250514170607.3000994-2-willy@infradead.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250514170607.3000994-1-willy@infradead.org> References: <20250514170607.3000994-1-willy@infradead.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: BCECB100016 X-Stat-Signature: hqm4zxhqmer8n7db83wou558pg1jqcsd X-Rspam-User: X-HE-Tag: 1747242379-253685 X-HE-Meta: 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 ZhCN8AJL pXWdFZjRjnS1a1Og/eFUeRKQNMVsnM7liiW1n8NxWnXFX0IUo1j4jNntLQj2+EZxfMd246zeuUIvYwArf/o6dnmTn94osUBbl50WtidXrGcVSDlvsT9jCY9ukfQeDkY/v9rj7p3rAsui70i6T7VZywGWuIYuWREalUxlwLmFv/Mqn4iFbr1k57l/teRpy6VAVopLEqskeXI+TIJ3jS6tZqodk1jlmiMbV0tOOUylhR9AZI3fSUNdNn2BxtkeACF4VPwKG0O5Z3GLSzrXhNfVE+hOW281rsv6+bgwYeDE3LcyLTlw4iAEQ9Niakg== 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: In commit c749d9b7ebbc (iov_iter: fix copy_page_from_iter_atomic() if KMAP_LOCAL_FORCE_MAP), Hugh correctly noted that if KMAP_LOCAL_FORCE_MAP is enabled, we must limit ourselves to PAGE_SIZE bytes per call to kmap_local(). The same problem exists in memcpy_from_folio(), memcpy_to_folio(), folio_zero_tail(), folio_fill_tail() and memcpy_from_file_folio(), so add folio_test_partial_kmap() to do this more succinctly. Signed-off-by: Matthew Wilcox (Oracle) Fixes: 00cdf76012ab (mm: add memcpy_from_file_folio()) Cc: stable@vger.kernel.org --- include/linux/highmem.h | 10 +++++----- include/linux/page-flags.h | 7 +++++++ 2 files changed, 12 insertions(+), 5 deletions(-) diff --git a/include/linux/highmem.h b/include/linux/highmem.h index 5c6bea81a90e..c698f8415675 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -461,7 +461,7 @@ static inline void memcpy_from_folio(char *to, struct folio *folio, const char *from = kmap_local_folio(folio, offset); size_t chunk = len; - if (folio_test_highmem(folio) && + if (folio_test_partial_kmap(folio) && chunk > PAGE_SIZE - offset_in_page(offset)) chunk = PAGE_SIZE - offset_in_page(offset); memcpy(to, from, chunk); @@ -489,7 +489,7 @@ static inline void memcpy_to_folio(struct folio *folio, size_t offset, char *to = kmap_local_folio(folio, offset); size_t chunk = len; - if (folio_test_highmem(folio) && + if (folio_test_partial_kmap(folio) && chunk > PAGE_SIZE - offset_in_page(offset)) chunk = PAGE_SIZE - offset_in_page(offset); memcpy(to, from, chunk); @@ -522,7 +522,7 @@ static inline __must_check void *folio_zero_tail(struct folio *folio, { size_t len = folio_size(folio) - offset; - if (folio_test_highmem(folio)) { + if (folio_test_partial_kmap(folio)) { size_t max = PAGE_SIZE - offset_in_page(offset); while (len > max) { @@ -560,7 +560,7 @@ static inline void folio_fill_tail(struct folio *folio, size_t offset, VM_BUG_ON(offset + len > folio_size(folio)); - if (folio_test_highmem(folio)) { + if (folio_test_partial_kmap(folio)) { size_t max = PAGE_SIZE - offset_in_page(offset); while (len > max) { @@ -597,7 +597,7 @@ static inline size_t memcpy_from_file_folio(char *to, struct folio *folio, size_t offset = offset_in_folio(folio, pos); char *from = kmap_local_folio(folio, offset); - if (folio_test_highmem(folio)) { + if (folio_test_partial_kmap(folio)) { offset = offset_in_page(offset); len = min_t(size_t, len, PAGE_SIZE - offset); } else diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index e6a21b62dcce..3b814ce08331 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -615,6 +615,13 @@ FOLIO_FLAG(dropbehind, FOLIO_HEAD_PAGE) PAGEFLAG_FALSE(HighMem, highmem) #endif +/* Does kmap_local_folio() only allow access to one page of the folio? */ +#ifdef CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP +#define folio_test_partial_kmap(f) true +#else +#define folio_test_partial_kmap(f) folio_test_highmem(f) +#endif + #ifdef CONFIG_SWAP static __always_inline bool folio_test_swapcache(const struct folio *folio) { -- 2.47.2