6.14-stable review patch. If anyone has any objections, please let me know.
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From: Johannes Thumshirn johannes.thumshirn@wdc.com
[ Upstream commit b0c26f47992672661340dd6ea931240213016609 ]
There was a bug report about a NULL pointer dereference in __btrfs_add_free_space_zoned() that ultimately happens because a conversion from the default metadata profile DUP to a RAID1 profile on two disks.
The stack trace has the following signature:
BTRFS error (device sdc): zoned: write pointer offset mismatch of zones in raid1 profile BUG: kernel NULL pointer dereference, address: 0000000000000058 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI RIP: 0010:__btrfs_add_free_space_zoned.isra.0+0x61/0x1a0 RSP: 0018:ffffa236b6f3f6d0 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff96c8132f3400 RCX: 0000000000000001 RDX: 0000000010000000 RSI: 0000000000000000 RDI: ffff96c8132f3410 RBP: 0000000010000000 R08: 0000000000000003 R09: 0000000000000000 R10: 0000000000000000 R11: 00000000ffffffff R12: 0000000000000000 R13: ffff96c758f65a40 R14: 0000000000000001 R15: 000011aac0000000 FS: 00007fdab1cb2900(0000) GS:ffff96e60ca00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000058 CR3: 00000001a05ae000 CR4: 0000000000350ef0 Call Trace: <TASK> ? __die_body.cold+0x19/0x27 ? page_fault_oops+0x15c/0x2f0 ? exc_page_fault+0x7e/0x180 ? asm_exc_page_fault+0x26/0x30 ? __btrfs_add_free_space_zoned.isra.0+0x61/0x1a0 btrfs_add_free_space_async_trimmed+0x34/0x40 btrfs_add_new_free_space+0x107/0x120 btrfs_make_block_group+0x104/0x2b0 btrfs_create_chunk+0x977/0xf20 btrfs_chunk_alloc+0x174/0x510 ? srso_return_thunk+0x5/0x5f btrfs_inc_block_group_ro+0x1b1/0x230 btrfs_relocate_block_group+0x9e/0x410 btrfs_relocate_chunk+0x3f/0x130 btrfs_balance+0x8ac/0x12b0 ? srso_return_thunk+0x5/0x5f ? srso_return_thunk+0x5/0x5f ? __kmalloc_cache_noprof+0x14c/0x3e0 btrfs_ioctl+0x2686/0x2a80 ? srso_return_thunk+0x5/0x5f ? ioctl_has_perm.constprop.0.isra.0+0xd2/0x120 __x64_sys_ioctl+0x97/0xc0 do_syscall_64+0x82/0x160 ? srso_return_thunk+0x5/0x5f ? __memcg_slab_free_hook+0x11a/0x170 ? srso_return_thunk+0x5/0x5f ? kmem_cache_free+0x3f0/0x450 ? srso_return_thunk+0x5/0x5f ? srso_return_thunk+0x5/0x5f ? syscall_exit_to_user_mode+0x10/0x210 ? srso_return_thunk+0x5/0x5f ? do_syscall_64+0x8e/0x160 ? sysfs_emit+0xaf/0xc0 ? srso_return_thunk+0x5/0x5f ? srso_return_thunk+0x5/0x5f ? seq_read_iter+0x207/0x460 ? srso_return_thunk+0x5/0x5f ? vfs_read+0x29c/0x370 ? srso_return_thunk+0x5/0x5f ? srso_return_thunk+0x5/0x5f ? syscall_exit_to_user_mode+0x10/0x210 ? srso_return_thunk+0x5/0x5f ? do_syscall_64+0x8e/0x160 ? srso_return_thunk+0x5/0x5f ? exc_page_fault+0x7e/0x180 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7fdab1e0ca6d RSP: 002b:00007ffeb2b60c80 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fdab1e0ca6d RDX: 00007ffeb2b60d80 RSI: 00000000c4009420 RDI: 0000000000000003 RBP: 00007ffeb2b60cd0 R08: 0000000000000000 R09: 0000000000000013 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffeb2b6343b R14: 00007ffeb2b60d80 R15: 0000000000000001 </TASK> CR2: 0000000000000058 ---[ end trace 0000000000000000 ]---
The 1st line is the most interesting here:
BTRFS error (device sdc): zoned: write pointer offset mismatch of zones in raid1 profile
When a RAID1 block-group is created and a write pointer mismatch between the disks in the RAID set is detected, btrfs sets the alloc_offset to the length of the block group marking it as full. Afterwards the code expects that a balance operation will evacuate the data in this block-group and repair the problems.
But before this is possible, the new space of this block-group will be accounted in the free space cache. But in __btrfs_add_free_space_zoned() it is being checked if it is a initial creation of a block group and if not a reclaim decision will be made. But the decision if a block-group's free space accounting is done for an initial creation depends on if the size of the added free space is the whole length of the block-group and the allocation offset is 0.
But as btrfs_load_block_group_zone_info() sets the allocation offset to the zone capacity (i.e. marking the block-group as full) this initial decision is not met, and the space_info pointer in the 'struct btrfs_block_group' has not yet been assigned.
Fail creation of the block group and rely on manual user intervention to re-balance the filesystem.
Afterwards the filesystem can be unmounted, mounted in degraded mode and the missing device can be removed after a full balance of the filesystem.
Reported-by: 西木野羰基 yanqiyu01@gmail.com Link: https://lore.kernel.org/linux-btrfs/CAB_b4sBhDe3tscz=duVyhc9hNE+gu=B8CrgLO15... Fixes: b1934cd60695 ("btrfs: zoned: handle broken write pointer on zones") Reviewed-by: Anand Jain anand.jain@oracle.com Signed-off-by: Johannes Thumshirn johannes.thumshirn@wdc.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/btrfs/zoned.c | 1 - 1 file changed, 1 deletion(-)
diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c index aaf925897fdda..978a57da8b4f5 100644 --- a/fs/btrfs/zoned.c +++ b/fs/btrfs/zoned.c @@ -1659,7 +1659,6 @@ int btrfs_load_block_group_zone_info(struct btrfs_block_group *cache, bool new) * stripe. */ cache->alloc_offset = cache->zone_capacity; - ret = 0; }
out: