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Howlett , ryan.roberts@arm.com, Vlastimil Babka , lance.yang@linux.dev, linux-kernel@vger.kernel.org, nphamcs@gmail.com, shikemeng@huaweicloud.com, yosry@kernel.org, qi.zheng@linux.dev, luizcap@redhat.com, kernel-team@meta.com, Usama Arif Subject: [PATCH v9 29/32] mm: don't PTE-batch a swap-in over a hardware-poisoned subpage Date: Thu, 5 Nov 2026 10:39:13 -0800 Message-ID: <20261105183940.2236717-30-usama.arif@linux.dev> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261105183940.2236717-1-usama.arif@linux.dev> References: <20261105183940.2236717-1-usama.arif@linux.dev> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit do_swap_page() checks PageHWPoison() on the faulting page, but the large-folio batching path then maps the rest of the folio without looking at the other subpages. A poisoned subpage that is not the one being faulted gets mapped anyway, and the fault that would have reported it never happens. Skip batching for such a folio and let each page take its own fault, where the existing check catches it. Test every subpage rather than the folio-level PG_has_hwpoisoned: memory_failure() sets PageHWPoison() on the subpage before it acquires the folio lock, which we hold here. Signed-off-by: Usama Arif --- mm/memory.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/mm/memory.c b/mm/memory.c index dedcec3cfca6e..47bba4695d855 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -5143,7 +5143,14 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) page_idx = 0; address = vmf->address; ptep = vmf->pte; - if (folio_test_large(folio) && folio_test_swapcache(folio)) { + /* + * Scan every subpage rather than testing the folio-level + * PG_has_hwpoisoned: memory_failure() sets PageHWPoison on the subpage + * before it takes the folio lock, and we hold that lock, so the + * folio-level flag can still be clear here. + */ + if (folio_test_large(folio) && folio_test_swapcache(folio) && + !folio_has_any_hwpoisoned_page(folio)) { const int nr = folio_nr_pages(folio); const unsigned long idx = folio_page_idx(folio, page); unsigned long folio_start, folio_end; -- 2.53.0-Meta