[PATCH v2 0/3] md/raid1,raid10: fix deadlock and bio accounting in read error path

Abd-Alrhman Masalkhi
2026-05-01T11:47:04Z

Hi,

This series revisits an issue in the read error recovery path for
raid1 and raid10 when bios are split and resubmitted.

In v1, the approach was to avoid splitting bios in the raid1 thread
to prevent recursion and potential deadlocks. However, this was not
ideal and too restrictive.

As suggested by Yu Kuai, this series instead handles the problem in
md_handle_request() and allows bio splitting.

Link to Yu Kuai' email: https://lore.kernel.org/linux-raid/m2lde74dtw.fsf@gmail.com/T/#m714020a38b60fc5f84b9a24f0c46acbe5d7342d6

This series fixes the above by:
- handling md cloned bios explicitly in md_handle_request()
- using md_cloned_bio() to reliably detect the error path
- fixing bio accounting to avoid double/missing accounting

Changes in v2:
- Split fixes into separate patches for clarity.
- Use md_cloned_bio() consistently to detect cloned bios.
- Recognize that raid10 has the same issue and fix it in this series
- Allow splitting bios.
- Handle md cloned bios explicitly in md_handle_request()
- Link v1: https://lore.kernel.org/linux-raid/20260427103446.300378-1-abd.masalkhi@gmail.com/

Abd-Alrhman Masalkhi (3):
md/raid1,raid10: fix deadlock in read error recovery path
md/raid1,raid10: fix error-path detection with md_cloned_bio()
md/raid1,raid10: fix bio accounting for split md cloned bios

drivers/md/md.c | 25 ++++++++++++++++---------
drivers/md/md.h | 5 +++++
drivers/md/raid1.c | 15 +++++++++++----
drivers/md/raid10.c | 28 ++++++++++++++++++----------
4 files changed, 50 insertions(+), 23 deletions(-)

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2.43.0