Re: md/bitmap: fix GPF in write_page caused by resize race

[Michał Mirosław]

Hi,

Commit 5f73c8b33df9 ("md/bitmap: fix GPF in write_page caused by resize
race") in stable 6.19 killed my machine. I confirmed that after reverting
this commit the machine boots fine. The same commit was backported into
6.18 stable and shows the same symptoms. I tried the revert only with 6.19,
though, as that revived my workflow.

For context, I have several md devices, some with internal bitmaps and
dm-crypt on top.  md3 and md4 belong to a single LVM VG. In the locked
up state I was able to see `mdadm`, some `udev-trigger` and `mount` tasks
all hanging in D state.

/proc/mdstat:

md9 : active raid1 sdc1[0] sdh1[1]
      547584 blocks super 1.0 [2/2] [UU]

md3 : active raid1 sdg3[3] sdb3[2]
      669920064 blocks super 1.2 [2/2] [UU]
      bitmap: 2/5 pages [8KB], 65536KB chunk

md0 : active raid1 sdb1[5] sda1[3]
      123892 blocks super 1.2 [3/2] [UU_]

md4 : active raid1 sde[0](W) nvme0n1[2] nvme1n1[3]
      488254464 blocks super 1.2 [3/3] [UUU]
      bitmap: 0/4 pages [0KB], 65536KB chunk

md1 : active raid1 sda2[2] nvme4n1p1[4]
      234305112 blocks super 1.2 [2/2] [UU]
      bitmap: 2/2 pages [8KB], 65536KB chunk

Best Regards
Michał Mirosław