[PATCH v3 0/2] x86/mce: Rate-limit messages from corrected error floods

[Breno Leitao <leitao@debian.org>]

A machine check bank that reports corrected errors at a high rate
makes the MCE code print two messages without any bound: "Machine
check events logged" for every error mce_log() queues, and "CMCI storm
detected" / "CMCI storm subsided" every time the bank enters or leaves
storm mode.

One host printed about 100 million "Machine check events logged" lines
an hour. On another, the storm notices were 82% of everything it wrote
to the kernel log.

Patch 1, from Rik, restores the two-per-minute limit that "Machine
check events logged" had before it moved into mce_log(). It is a fix
and is tagged for stable.

Patch 2 puts both storm notices behind one ratelimit, with the default
interval and burst.

Only the messages are limited. The errors are still logged and storm
handling is unchanged.

Both patches were posted separately before. Borislav asked to merge
them into one series [1].

[1] https://lore.kernel.org/r/20261112182125.GDavYDpdJpmpU2Piyu@fat_crate.local

Signed-off-by: Breno Leitao <leitao@debian.org>
---
Changes in v3:
- Add Rik's "x86/mce: Restore rate limit on MCE logged message" as
  patch 1 (Borislav). It carries the Reviewed-by tags from its
  posting; only its first changelog sentence changed (typo, commit
  reference style).
- Link to Rik's posting: https://patch.msgid.link/20261108143751.3af49e48@fangorn
- Link to v2: https://patch.msgid.link/20261112-mci_ratelimit-v2-1-a9e67055526b@debian.org

Changes in v2:
- rebased on linux-next
- Link to v1: https://patch.msgid.link/20260827-mci_ratelimit-v1-1-ac43df769b36@debian.org

---
Breno Leitao (1):
      x86/mce: Rate-limit the CMCI storm transition notices

Rik van Riel (1):
      x86/mce: Restore rate limit on MCE logged message

 arch/x86/kernel/cpu/mce/core.c      |  6 +++++-
 arch/x86/kernel/cpu/mce/threshold.c | 16 ++++++++++++++--
 2 files changed, 19 insertions(+), 3 deletions(-)
---
base-commit: aaa2f954c21b205a0bcd0961e5b2be4e82e58455
change-id: 20260827-mci_ratelimit-064421e2d8cd

Best regards,
--  
Breno Leitao <leitao@debian.org>