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Tue, 29 Sep 2026 08:19:57 +0000 X-Mizu-Trace-ID: 89245958c046eafb X-Migadu-Flow: FLOW_OUT From: Hao Ge To: Suren Baghdasaryan , =Kent Overstreet , Luis Chamberlain , Petr Pavlu , Daniel Gomez , Sami Tolvanen , Aaron Tomlin , Andrew Morton , Alexander Potapenko , Marco Elver , Dmitry Vyukov , Vlastimil Babka , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , Uladzislau Rezki Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-modules@vger.kernel.org, kasan-dev@googlegroups.com, Hao Ge , Sashiko , stable@vger.kernel.org Subject: [PATCH v11 2/7] mm/vmalloc: undo partial mappings inside the mapping functions Date: Tue, 29 Sep 2026 16:20:09 +0800 Message-Id: <20260929082014.160587-3-hao.ge@linux.dev> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20260929082014.160587-1-hao.ge@linux.dev> References: <20260929082014.160587-1-hao.ge@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: BE4E320004 X-Rspam-User: X-Stat-Signature: ktc14uyxjiqzt9dezrk7gaus8motab4o X-HE-Tag: 1790669998-474928 X-HE-Meta: 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 L4EXY4/M kKgCmYrKY9LORZKe/HBgOy4plcUOZefAy5lsZJmVSpmvfQ+MqDz9iTK6wtPbKjdErA78N3sk0TyqcFpheZ7HrtfMH2esHP4dkSNWFvDU8S7xjvQ+lvF8cPF2sd8QZbS121k6uUGFOT5bQ/xxyLyWyBCw7qCURJS2z5wdaJuoEdtm1lPFtEp9BBoXHp+YCz7jOUMEXboYFv6Nzq0+vUntbN0+GRnB52q1GLANFQPafaBg+B9MNnKHRVN98J2LkIkJze3Kz Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: __vmap_pages_range_noflush() and friends can install some PTEs before failing and leave them mapped, and the kernel callers do not agree on who cleans them up. For example, pcpu_map_pages() and kmsan_ioremap_page_range() unmap the leftovers themselves, while vm_module_tags_populate() and the __GFP_NOFAIL retry loop in __vmalloc_area_node() relied on the mapping functions cleaning up and did not call anything like vunmap_range() themselves. When the same range is mapped again, the attempt hits the leftovers and fails, with BUG() in vmap_pte_range() for huge mappings. After discussing with Suren and Ulad, we decided the cleanup belongs to __vmap_pages_range_noflush() and friends, so the callers no longer need to unmap the partial mappings themselves. Each function now undoes the PTEs it installed itself. The rollback calls the low-level __vunmap_range_noflush(), it just clears the PTEs of the range it is given, which is all a rollback needs. It cannot use vunmap_range_noflush() because these mapping functions also map the KMSAN shadow and origin, and for a metadata range its hook would look up the metadata of the metadata, get 0 and BUG() on addr >= end. The failed mappings were never accessed, no TLB flush needed. Fixes: 9376130c390a ("mm/vmalloc: add support for __GFP_NOFAIL") Fixes: 0f9b685626da ("alloc_tag: populate memory for module tags as needed") Reported-by: Sashiko Cc: stable@vger.kernel.org Signed-off-by: Hao Ge --- mm/kmsan/shadow.c | 4 ++++ mm/vmalloc.c | 31 +++++++++++++++++++++++++++++-- 2 files changed, 33 insertions(+), 2 deletions(-) diff --git a/mm/kmsan/shadow.c b/mm/kmsan/shadow.c index 0c88d89bf0d6..2166086d3dc3 100644 --- a/mm/kmsan/shadow.c +++ b/mm/kmsan/shadow.c @@ -258,6 +258,10 @@ int kmsan_vmap_pages_range_noflush(unsigned long start, unsigned long end, o_pages, page_shift); kmsan_leave_runtime(); if (mapped) { + /* Undo the shadow mapping set up above. */ + kmsan_enter_runtime(); + __vunmap_range_noflush(shadow_start, shadow_end); + kmsan_leave_runtime(); err = mapped; goto ret; } diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 859e6d2d57a3..9bbf75706627 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -349,6 +349,10 @@ static int vmap_range_noflush(unsigned long addr, unsigned long end, if (mask & ARCH_PAGE_TABLE_SYNC_MASK) arch_sync_kernel_mappings(start, end); + /* Undo the PTEs installed before the failure. */ + if (err) + __vunmap_range_noflush(start, end); + return err; } @@ -363,6 +367,9 @@ int vmap_page_range(unsigned long addr, unsigned long end, if (!err) err = kmsan_ioremap_page_range(addr, end, phys_addr, prot, ioremap_max_page_shift); + if (err) + __vunmap_range_noflush(addr, end); + return err; } @@ -667,6 +674,10 @@ static int vmap_small_pages_range_noflush(unsigned long addr, unsigned long end, if (mask & ARCH_PAGE_TABLE_SYNC_MASK) arch_sync_kernel_mappings(start, end); + /* Undo the PTEs installed before the failure. */ + if (err) + __vunmap_range_noflush(start, end); + return err; } @@ -683,6 +694,7 @@ int __vmap_pages_range_noflush(unsigned long addr, unsigned long end, pgprot_t prot, struct page **pages, unsigned int page_shift) { unsigned int i, nr = (end - addr) >> PAGE_SHIFT; + unsigned long start = addr; WARN_ON(page_shift < PAGE_SHIFT); @@ -696,8 +708,14 @@ int __vmap_pages_range_noflush(unsigned long addr, unsigned long end, err = vmap_range_noflush(addr, addr + (1UL << page_shift), page_to_phys(pages[i]), prot, page_shift); - if (err) + if (err) { + /* + * vmap_range_noflush() undoes its own partial work, + * discard the chunks that already mapped. + */ + __vunmap_range_noflush(start, addr); return err; + } addr += 1UL << page_shift; } @@ -714,7 +732,16 @@ int vmap_pages_range_noflush(unsigned long addr, unsigned long end, if (ret) return ret; - return __vmap_pages_range_noflush(addr, end, prot, pages, page_shift); + + ret = __vmap_pages_range_noflush(addr, end, prot, pages, page_shift); + /* + * The page tables undo themselves on failure. Tear down the + * metadata that was fully set up before the mapping failed. + */ + if (ret) + kmsan_vunmap_range_noflush(addr, end); + + return ret; } static int __vmap_pages_range(unsigned long addr, unsigned long end, -- 2.25.1