[PATCH v4 0/3] mm/memory-failure: add panic option for unrecoverable pages

Breno Leitao
2026-04-15T12:55:50Z

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 <leitao@debian.org>
---
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 <leitao@debian.org>