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[34.83.123.78]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-39e6fb75539sm5863046a91.3.2026.09.19.15.17.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 19 Sep 2026 15:17:33 -0700 (PDT) From: Hui Peng To: miklos@szeredi.hu Cc: fuse-devel@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [PATCH] fuse: validate folio state before pipe_buf_try_steal() in fuse_try_move_folio() Date: Sat, 19 Sep 2026 22:17:33 +0000 Message-ID: <20260919221733.3707924-1-benquike@gmail.com> X-Mailer: git-send-email 2.55.0.1082.g2b9226bbc0-goog Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit In fuse_try_move_folio(), check that the pipe buffer's folio is not hugetlb, swap-backed, or already mapped/anon before attempting pipe_buf_try_steal() and inserting it into the FUSE inode's page cache, preventing VM_BUG_ON_FOLIO() and page cache state corruption. Fixes: 394244b24fdd ("fuse: support copying large folios") Assisted-by: LLM Signed-off-by: Hui Peng --- diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index 4fec31fc0b84..121bb1f3cb05 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -1147,32 +1147,32 @@ static int fuse_try_move_folio(struct fuse_copy_state *cs, struct folio **foliop if (cs->len != folio_size(oldfolio)) goto out_fallback; - if (!pipe_buf_try_steal(cs->pipe, buf)) - goto out_fallback; - newfolio = page_folio(buf->page); - folio_clear_uptodate(newfolio); - folio_clear_mappedtodisk(newfolio); - if (folio_test_large(newfolio)) - goto out_fallback_unlock; - - if (fuse_check_folio(newfolio) != 0) - goto out_fallback_unlock; + goto out_fallback; /* * This is a new and locked page, it shouldn't be mapped or * have any special flags on it */ if (WARN_ON(folio_mapped(oldfolio))) - goto out_fallback_unlock; + goto out_fallback; if (WARN_ON(folio_has_private(oldfolio))) - goto out_fallback_unlock; + goto out_fallback; if (WARN_ON(folio_test_dirty(oldfolio) || folio_test_writeback(oldfolio))) - goto out_fallback_unlock; + goto out_fallback; if (WARN_ON(folio_test_mlocked(oldfolio))) + goto out_fallback; + + if (!pipe_buf_try_steal(cs->pipe, buf)) + goto out_fallback; + + folio_clear_uptodate(newfolio); + folio_clear_mappedtodisk(newfolio); + + if (fuse_check_folio(newfolio) != 0) goto out_fallback_unlock; err = lock_request(cs->req);