On Wed, Dec 11, 2019 at 04:55:53PM +0100, David Sterba wrote: > On Wed, Dec 11, 2019 at 09:58:45AM -0500, Josef Bacik wrote: > > On 12/10/19 11:00 PM, Chris Murphy wrote: > > > Could continue to chat in one application, the desktop environment was > > > responsive, but no shells worked and I couldn't get to a tty and I > > > couldn't ssh into remotely. Looks like the journal has everything up > > > until I pressed and held down the power button. > > > > > > > > > /dev/nvme0n1p7 on / type btrfs > > > (rw,noatime,seclabel,compress=zstd:1,ssd,space_cache=v2,subvolid=274,subvol=/root) > > > > > > dmesg pretty > > > https://pastebin.com/pvG3ERnd > > > > > > dmesg (likely MUA stomped) > > > [10224.184137] flap.local kernel: perf: interrupt took too long (2522 > > >> 2500), lowering kernel.perf_event_max_sample_rate to 79000 > > > [14712.698184] flap.local kernel: perf: interrupt took too long (3153 > > >> 3152), lowering kernel.perf_event_max_sample_rate to 63000 > > > [17903.211976] flap.local kernel: Lockdown: systemd-logind: > > > hibernation is restricted; see man kernel_lockdown.7 > > > [22877.667177] flap.local kernel: BUG: kernel NULL pointer > > > dereference, address: 00000000000006c8 > > > [22877.667182] flap.local kernel: #PF: supervisor read access in kernel mode > > > [22877.667184] flap.local kernel: #PF: error_code(0x0000) - not-present page > > > [22877.667187] flap.local kernel: PGD 0 P4D 0 > > > [22877.667191] flap.local kernel: Oops: 0000 [#1] SMP PTI > > > [22877.667194] flap.local kernel: CPU: 2 PID: 14747 Comm: kworker/u8:7 > > > Not tainted 5.5.0-0.rc1.git0.1.fc32.x86_64+debug #1 > > > [22877.667196] flap.local kernel: Hardware name: HP HP Spectre > > > Notebook/81A0, BIOS F.43 04/16/2019 > > > [22877.667226] flap.local kernel: Workqueue: btrfs-delalloc > > > btrfs_work_helper [btrfs] > > > [22877.667233] flap.local kernel: RIP: > > > 0010:bio_associate_blkg_from_css+0x1c/0x3b0 > > > > This looks like the extent_map bdev cleanup thing that was supposed to be fixed, > > did you send the patch without the fix for it Dave? Thanks, > > The fix for NULL bdev was added in 429aebc0a9a063667dba21 (and tested > with cgroups v2) and it's in a different function than the one that > appears on the stacktrace. > > This seems to be another instance where the bdev is needed right after > the bio is created but way earlier than it's actually known for real, > yet still needed for the blkcg thing. > > 443 bio = btrfs_bio_alloc(first_byte); > 444 bio->bi_opf = REQ_OP_WRITE | write_flags; > 445 bio->bi_private = cb; > 446 bio->bi_end_io = end_compressed_bio_write; > 447 > 448 if (blkcg_css) { > 449 bio->bi_opf |= REQ_CGROUP_PUNT; > 450 bio_associate_blkg_from_css(bio, blkcg_css); > 451 } > > Strange that it takes so long to reproduce, meaning the 'if' branch is > not taken often. Compile tested only: --- a/fs/btrfs/compression.c +++ b/fs/btrfs/compression.c @@ -446,6 +446,7 @@ blk_status_t btrfs_submit_compressed_write(struct inode *inode, u64 start, bio->bi_end_io = end_compressed_bio_write; if (blkcg_css) { + bio_set_bev(bio, fs_info->fs_devices->latest_bdev); bio->bi_opf |= REQ_CGROUP_PUNT; bio_associate_blkg_from_css(bio, blkcg_css); }
