Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

bcachefs: grab s_umount only if snapshotting

When I was testing mongodb over bcachefs with compression, there is a lockdep warning when snapshotting mongodb data volume.

$ cat test.sh prog=bcachefs

$prog subvolume create /mnt/data $prog subvolume create /mnt/data/snapshots

while true;do $prog subvolume snapshot /mnt/data /mnt/data/snapshots/$(date +%s) sleep 1s done

$ cat /etc/mongodb.conf systemLog: destination: file logAppend: true path: /mnt/data/mongod.log

storage: dbPath: /mnt/data/

lockdep reports: [ 3437.452330] ====================================================== [ 3437.452750] WARNING: possible circular locking dependency detected [ 3437.453168] 6.7.0-rc7-custom+ #85 Tainted: G E [ 3437.453562] ------------------------------------------------------ [ 3437.453981] bcachefs/35533 is trying to acquire lock: [ 3437.454325] ffffa0a02b2b1418 (sb_writers#10){.+.+}-{0:0}, at: filename_create+0x62/0x190 [ 3437.454875] but task is already holding lock: [ 3437.455268] ffffa0a02b2b10e0 (&type->s_umount_key#48){.+.+}-{3:3}, at: bch2_fs_file_ioctl+0x232/0xc90 [bcachefs] [ 3437.456009] which lock already depends on the new lock.

[ 3437.456553] the existing dependency chain (in reverse order) is: [ 3437.457054] -> #3 (&type->s_umount_key#48){.+.+}-{3:3}: [ 3437.457507] down_read+0x3e/0x170 [ 3437.457772]…