On Wed, Nov 21, 2018 at 05:10:52PM +0200, Nikolay Borisov wrote: > Running btrfs/124 in a loop hung up on me sporadically with the > following call trace: > btrfs D 0 5760 5324 0x00000000 > Call Trace: > ? __schedule+0x243/0x800 > schedule+0x33/0x90 > btrfs_start_ordered_extent+0x10c/0x1b0 [btrfs] > ? wait_woken+0xa0/0xa0 > btrfs_wait_ordered_range+0xbb/0x100 [btrfs] > btrfs_relocate_block_group+0x1ff/0x230 [btrfs] > btrfs_relocate_chunk+0x49/0x100 [btrfs] > btrfs_balance+0xbeb/0x1740 [btrfs] > btrfs_ioctl_balance+0x2ee/0x380 [btrfs] > btrfs_ioctl+0x1691/0x3110 [btrfs] > ? lockdep_hardirqs_on+0xed/0x180 > ? __handle_mm_fault+0x8e7/0xfb0 > ? _raw_spin_unlock+0x24/0x30 > ? __handle_mm_fault+0x8e7/0xfb0 > ? do_vfs_ioctl+0xa5/0x6e0 > ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs] > do_vfs_ioctl+0xa5/0x6e0 > ? entry_SYSCALL_64_after_hwframe+0x3e/0xbe > ksys_ioctl+0x3a/0x70 > __x64_sys_ioctl+0x16/0x20 > do_syscall_64+0x60/0x1b0 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > > This happens because during page writeback it's valid for > writepage_delalloc to instantiate a delalloc range which doesn't > belong to the page currently being written back. > > The reason this case is valid is due to find_lock_delalloc_range > returning any available range after the passed delalloc_start and > ignorting whether the page under writeback is within that range. > In turn ordered extents (OE) are always created for the returned range > from find_lock_delalloc_range. If, however, a failure occurs while OE > are being created then the clean up code in btrfs_cleanup_ordered_extents > will be called. > > Unfortunately the code in btrfs_cleanup_ordered_extents doesn't consider > the case of such 'foreign' range being processed and instead it always > assumes that the range OE are created for belongs to the page. This > leads to the first page of such foregin range to not be cleaned up since > it's deliberately missed skipped by the current cleaning up code. > > Fix this by correctly checking whether the current page belongs to the > range being instantiated and if so adjsut the range parameters > passed for cleaning up. If it doesn't, then just clean the whole OE > range directly. > > Signed-off-by: Nikolay Borisov <nbori...@suse.com> > Reviewed-by: Josef Bacik <jo...@toxicpanda.com>
Added to misc-next, thanks.
