Similar to bug 104571 (https://bugzilla.kernel.org/show_bug.cgi?id=104571), we have observed this. Excerpt from dmesg: [86808.174336] EXT4-fs (sda2): error count since last fsck: 12 [86808.174345] EXT4-fs (sda2): initial error at time 1458455103: ext4_mb_generate_buddy:757 [86808.174347] EXT4-fs (sda2): last error at time 1458572059: ext4_remount:4849: inode 8524962: block 34112270 [94597.670282] [sched_delayed] sched: RT throttling activated [173315.491461] EXT4-fs (sda2): error count since last fsck: 12 [173315.491468] EXT4-fs (sda2): initial error at time 1458455103: ext4_mb_generate_buddy:757 [173315.491470] EXT4-fs (sda2): last error at time 1458572059: ext4_remount:4849: inode 8524962: block 34112270 [190512.378738] rsync[85653]: unhandled signal 11 at 00003fffe48d0000 nip 00003fff972fd054 lr 00003fff972f6560 code 30001 [212232.198189] rsync[88408]: unhandled signal 11 at 00003fffeb8f0000 nip 00003fffa475d054 lr 00003fffa4756560 code 30001 [226392.672509] rsync[90221]: unhandled signal 11 at 00003fffc6460000 nip 00003fff983cd054 lr 00003fff983c6560 code 30001 [227413.044157] rsync[90355]: unhandled signal 11 at 00003fffe93f0000 nip 00003fff7831d054 lr 00003fff78316560 code 30001 [241933.061143] rsync[92307]: unhandled signal 11 at 00003ffff9e70000 nip 00003fffb430d054 lr 00003fffb4306560 code 30001 [247565.478035] EXT4-fs error (device sda2): ext4_mb_generate_buddy:757: group 2003, block bitmap and bg descriptor inconsistent: 146 vs 145 free clusters [247565.478052] Aborting journal on device sda2-8. [247565.482212] EXT4-fs (sda2): Remounting filesystem read-only [247565.513031] EXT4-fs error (device sda2): ext4_journal_check_start:56: [247565.513034] EXT4-fs error (device sda2): ext4_journal_check_start:56: [247565.513038] EXT4-fs error (device sda2): ext4_journal_check_start:56: Detected aborted journal [247565.513039] Detected aborted journal [247565.513051] EXT4-fs error (device sda2): ext4_journal_check_start:56: Detected aborted journal [247565.513056] Detected aborted journal [247565.513080] EXT4-fs error (device sda2): ext4_journal_check_start:56: Detected aborted journal
Are you running this under KVM? The most recent spate of complaints about this (which just means that ext4 discovered an inconsistency in the allocation bitmaps; it doesn't automatically mean it's an ext4 bug) was caused by a bug in the hypervisor layer of the Host OS. See the resolution of this bug: https://bugzilla.kernel.org/show_bug.cgi?id=102731