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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, Breno Leitao , kernel-team@meta.com X-Mailer: b4 0.16-dev-453a6 X-Developer-Signature: v=1; a=openpgp-sha256; l=4428; i=leitao@debian.org; h=from:subject:message-id; bh=ooqEvy5RJLVNe8O7dJAeTYBomhd/oOnKcXQmFHXWZ0c=; b=owEBbQKS/ZANAwAIATWjk5/8eHdtAcsmYgBp34rHlDVyi74jWKjoFIyrfuD1lU9NC94kYqtNa rxjhMVfyxaJAjMEAAEIAB0WIQSshTmm6PRnAspKQ5s1o5Of/Hh3bQUCad+KxwAKCRA1o5Of/Hh3 bfaoEACfT0yRyfwkUbkyCtIBIcPgZhyc3UjA5YMPy7cZyHiTsjEK2UEy8QIj60IPwKcUpq0rWgP aNmyhJDfHFcXgs0ec9z/y+mPBjAHuUgg8IIYhPMAkGGcfkoZeA2/PivNoSsx1wE55yu4OP3/Av0 un0pRYOKDqSlujYetUjTSyK0nZvY/AAbPynIUBXSZs0zi8X2DWlU+WO2yJX1sNvl2yrznGJb0xY WMX4g8iShGeaXbCkOMJ1NC9+mZkfskHda3+7VXY3MnBqo0IX5agrbm5hVfCswcMGHG8q6nhuTjh yMHhJLsi2lFVfclTZzm1yqOS1+TnWVjj07X8U4W4IWPR4/czteKwmMR/DE02aFyArQ5fksTn7J3 60DHkszYGikQ48mpDWkWrcBm3Nn3yzgY8xKm4v3mFbVrlWi4RyEZ7jV9vdW6NdZ+kQKo2nzE+y4 i2OGz+hkJsz3S/jLrt60gl7B5jZTaooQBfz/nwyZmnNeyDu81ndXkBPC6KvnKgH9mq4eVHMqCMf exPMVVlV3xzg53re5bhogd79RpXy9oUfu+C1AKS6D/7phD1vdowneW2WMjugWhPvQ6zgzJQEE7e Boj8mmhb0N8d1lwDTKMJdcEe538llr9KIrbtZIR6r/+xdXPQeZPDu2sxDA4VgtCBEUvTBHRlzVK kemWvKRJNUwOaeA== X-Developer-Key: i=leitao@debian.org; a=openpgp; fpr=AC8539A6E8F46702CA4A439B35A3939FFC78776D X-Debian-User: leitao X-Rspamd-Queue-Id: DB060160003 X-Stat-Signature: iep49zprk9pnr38i5khu41zt1mjeg1hy X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1776257751-855390 X-HE-Meta: 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 kWmvDC0a xtYvSdoNWVs0YcgPDFXXoQZ6H/SZI6Pq7DonD4zcFSUOaFT82gRoa1u80kOKm5GCUM25zQ9POIMUtC7MFQM0GqYX2ycqd94KwYEF0PDjdaQLx1j/NtTSJylwwXYkRcD6dWUyzsuJldFZrQJTER+pymIoqPbroGvi6bfu0kO1MRbruZ8mPL8D+vUFotVI4GqacwzqlYzO8/UxL83PgoJiwMftKb8RveCes9NP+Qlnm5CrFpFi0eMAlT294yZGiQiPpAedOMexEIa5ls4J9vAFuTVIdFU/ymaFT3AIp6yt6akK7HUQ8i1y0EnAO5nlJnBEPmZbz Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: When the memory failure handler encounters an in-use kernel page that it cannot recover (slab, page tables, kernel stacks, vmalloc, etc.), it currently logs the error as "Ignored" and continues operation. This leaves corrupted data accessible to the kernel, which will inevitably cause either silent data corruption or a delayed crash when the poisoned memory is next accessed. This is a common problem on large fleets. We frequently observe multi-bit ECC errors hitting kernel slab pages, where memory_failure() fails to recover them and the system crashes later at an unrelated code path, making root cause analysis unnecessarily difficult. Here is one specific example from production on an arm64 server: a multi-bit ECC error hit a dentry cache slab page, memory_failure() failed to recover it (slab pages are not supported by the hwpoison recovery mechanism), and 67 seconds later d_lookup() accessed the poisoned cache line causing a synchronous external abort: [88690.479680] [Hardware Error]: error_type: 3, multi-bit ECC [88690.498473] Memory failure: 0x40272d: unhandlable page. [88690.498619] Memory failure: 0x40272d: recovery action for get hwpoison page: Ignored ... [88757.847126] Internal error: synchronous external abort: 0000000096000410 [#1] SMP [88758.061075] pc : d_lookup+0x5c/0x220 This series adds a new sysctl vm.panic_on_unrecoverable_memory_failure (default 0) that, when enabled, panics immediately on unrecoverable memory failures. This provides a clean crash dump at the time of the error, which is far more useful for diagnosis than a random crash later at an unrelated code path. This also categorizes reserved pages as MF_MSG_KERNEL, and panics on unknown page types (MF_MSG_UNKNOWN). Note that dynamically allocated kernel memory (SLAB/SLUB, vmalloc, kernel stacks, page tables) shares the MF_MSG_GET_HWPOISON return path with transient refcount races, so it is intentionally excluded from the panic conditions to avoid false positives. Signed-off-by: Breno Leitao --- Changes in v4: - Drop CONFIG_BOOTPARAM_MEMORY_FAILURE_PANIC kernel configuration option. - Split the reserved page classification (MF_MSG_KERNEL) into its own patch, separate from the panic mechanism. - Document why the buddy allocator TOCTOU race (between get_hwpoison_page() and is_free_buddy_page()) cannot cause false positives: PG_hwpoison is set beforehand and check_new_page() in the page allocator rejects hwpoisoned pages. - Document the narrow LRU isolation race window for MF_MSG_UNKNOWN and its mitigation via identify_page_state()'s two-pass design. - Explicitly document why MF_MSG_GET_HWPOISON is excluded from the panic conditions (shared path with transient races and non-reserved kernel memory). - Link to v3: https://patch.msgid.link/20260413-ecc_panic-v3-0-1dcbb2f12bc4@debian.org Changes in v3: - Rename is_unrecoverable_memory_failure() to panic_on_unrecoverable_mf() as suggested by maintainer. - Add CONFIG_BOOTPARAM_MEMORY_FAILURE_PANIC kernel configuration option, similar to CONFIG_BOOTPARAM_HARDLOCKUP_PANIC. - Add documentation for the sysctl and CONFIG option. - Add code comments documenting the panic condition design rationale and how the retry mechanism mitigates false positives from buddy allocator races. - Link to v2: https://patch.msgid.link/20260331-ecc_panic-v2-0-9e40d0f64f7a@debian.org Changes in v2: - Panic on MF_MSG_KERNEL, MF_MSG_KERNEL_HIGH_ORDER and MF_MSG_UNKNOWN instead of MF_MSG_GET_HWPOISON. - Report MF_MSG_KERNEL for reserved pages when get_hwpoison_page() fails instead of MF_MSG_GET_HWPOISON. - Link to v1: https://patch.msgid.link/20260323-ecc_panic-v1-0-72a1921726c5@debian.org --- Breno Leitao (3): mm/memory-failure: report MF_MSG_KERNEL for reserved pages mm/memory-failure: add panic option for unrecoverable pages Documentation: document panic_on_unrecoverable_memory_failure sysctl Documentation/admin-guide/sysctl/vm.rst | 37 +++++++++++++ mm/memory-failure.c | 92 ++++++++++++++++++++++++++++++++- 2 files changed, 128 insertions(+), 1 deletion(-) --- base-commit: e6efabc0afca02efa263aba533f35d90117ab283 change-id: 20260323-ecc_panic-4e473b83087c Best regards, -- Breno Leitao