[PATCH-next 0/2] dm: fix quiesce asymmetry and null pointer in suspend/load race

[Zheng Qixing]

From: Zheng Qixing <zhengqixing@xxxxxxxxxx>

Hello,

During reliability testing of the dm module, we discovered two bugs when
performing create/remove and suspend/resume operations at high frequency.

Analysis revealed that race conditions between suspend and table load
operations cause asymmetric handling of q->quiesce_depth and null pointer
dereference issues with q->tag_set.

To address the q->tag_set null pointer issue, patch 2 determines whether
to perform certain suspend actions for request-based devices based on the
existence of the table (map).

For detailed information, please refer to the patch commits.

Additionally, since modern Linux kernels have indeed transitioned to
multi-queue as the default (and single-queue is largely deprecated),
is using queue_is_mq() to determine dm_request_based() obsolete?

Zheng Qixing (2):
  dm: fix queue start/stop imbalance under suspend/load/resume races
  dm: fix NULL pointer dereference in __dm_suspend()

 drivers/md/dm-core.h |  1 +
 drivers/md/dm.c      | 13 ++++++++-----
 2 files changed, 9 insertions(+), 5 deletions(-)

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2.39.2