On Thu, Jan 4, 2024 at 5:39 AM Li Lingfeng [off-list ref] wrote:

From: Li Lingfeng <redacted>

Since md_start_sync() will be called without the protect of mddev_lock,
and it can run concurrently with array reconfiguration, traversal of rdev
in it should be protected by RCU lock.
Commit bc08041b32ab ("md: suspend array in md_start_sync() if array need
reconfiguration") added md_spares_need_change() to md_start_sync(),
casusing use of rdev without any protection.
Fix this by adding RCU lock in md_spares_need_change().

Fixes: bc08041b32ab ("md: suspend array in md_start_sync() if array need reconfiguration")
Signed-off-by: Li Lingfeng <redacted>

Looks good to me. Applied to md-tmp-6.9.

Thanks,
Song