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Tue, 10 Nov 2026 11:25:10 +0000 X-Mizu-Trace-ID: aaa1849df80259f7 X-Migadu-Flow: FLOW_OUT From: Hao Ge To: Uladzislau Rezki , Dev Jain , Suren Baghdasaryan , Andrew Morton , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , "Christophe Leroy (CS GROUP)" , "Ritesh Harjani (IBM)" , Shrikanth Hegde , Alexander Potapenko , Marco Elver , Dmitry Vyukov , Dennis Zhou , Tejun Heo , Christoph Lameter Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, Hao Ge , Sashiko Subject: [PATCH v4 6/9] mm/vmalloc: only flush the cache after the vmap succeeded Date: Tue, 10 Nov 2026 19:25:43 +0800 Message-Id: <20261110112546.261415-7-hao.ge@linux.dev> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20261110112546.261415-1-hao.ge@linux.dev> References: <20261110112546.261415-1-hao.ge@linux.dev> X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: 1k9nqccweukq7kzust8b8pnruo85sffd X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: BFCC21A0008 X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-HE-Tag: 1794309914-98967 X-HE-Meta: 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 pOWJzcT7 72Mfbr8nS/h8833KmLBuQCHhozuPETEAFy+gdGugZ5GVD3ORqPwpb1bURc+VBB80+RNebRFqoyVoJKJ2tKAl5u6rPtrBIrKauXxEil3F4MkqNdnAtUMsFRXwu1k5d/QsbfNaVStJaGTZ9Kn7cG6yJr5zSdmENzfdkdygxkrhN+UCrC40aTvSIGjpsDX4YF8b5/y9lQHO+gA2/RWV7u1ceuN6RrAu6Lvkdm0F17s1oIr4+t99eBpemXw1hDN77ZBzZpvW0VQQ1/IzKEe5Am1rE5LC4bW+4eYQ21bUoteuPtN3gJQAW5FGnkf0vYukLDUX4ZHE3ltcPdq5lg+0= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 vmap_page_range() and __vmap_pages_range() call flush_cache_vmap() before they even look at the error code. A failed mapping is never used, so the flush is pointless at best. According to the Sashiko review it is worse than pointless on UML: flush_cache_vmap() there is flush_tlb_kernel_range(), which syncs the PTEs into the host OS. Flushing a half-installed mapping therefore leaves host mappings behind for a range that was just freed again. Only flush when the mapping, and for vmap_page_range() also the KMSAN metadata, is fully set up. Reported-by: Sashiko Signed-off-by: Hao Ge --- mm/vmalloc.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 0565cbfe325c..3f98056f8c7e 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -369,10 +369,12 @@ int vmap_page_range(unsigned long addr, unsigned long end, err = vmap_range_noflush(addr, end, phys_addr, pgprot_nx(prot), ioremap_max_page_shift); - flush_cache_vmap(addr, end); if (!err) err = kmsan_ioremap_page_range(addr, end, phys_addr, prot, ioremap_max_page_shift); + if (!err) + flush_cache_vmap(addr, end); + return err; } @@ -758,7 +760,9 @@ static int __vmap_pages_range(unsigned long addr, unsigned long end, int err; err = vmap_pages_range_noflush(addr, end, prot, pages, page_shift, gfp_mask); - flush_cache_vmap(addr, end); + if (!err) + flush_cache_vmap(addr, end); + return err; } -- 2.25.1