BUG: unable to handle kernel NULL pointer dereference in mempool_alloc

Kernel	Title	Rank 🛈	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	BUG: unable to handle kernel NULL pointer dereference in mempool_alloc_noprof (2) bcachefs	10	C	done		8	88d	104d	29/29	fixed on 2025/09/04 16:56
upstream	BUG: unable to handle kernel NULL pointer dereference in mempool_alloc_noprof block	10				3	445d	474d	0/29	auto-obsoleted due to no activity on 2024/09/23 15:37

bcachefs (loop0): compression opt none set but not marked in superblock, fixing
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 0 P4D 0 
Oops: Oops: 0010 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5383 Comm: bch-rebalance/l Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 0018:ffffc9000d49ec18 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffff8880532c75a0
RDX: 1ffff1100a658eb4 RSI: 0000000000000000 RDI: 0000000000092800
RBP: ffffc9000d49ed70 R08: ffffc9000d49ece7 R09: 0000000000000000
R10: ffffc9000d49ecc0 R11: 0000000000000000 R12: 1ffff92001a93d94
R13: ffff8880532c75a0 R14: 0000000000092c40 R15: 0000000000092800
FS:  0000000000000000(0000) GS:ffff88808d20c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000000400eb000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 mempool_alloc_noprof+0x1a4/0x510 mm/mempool.c:406
 __bio_compress fs/bcachefs/compress.c:461 [inline]
 bch2_bio_compress+0x42f/0x14c0 fs/bcachefs/compress.c:555
 bch2_write_extent fs/bcachefs/io_write.c:1060 [inline]
 __bch2_write+0xfb5/0x3900 fs/bcachefs/io_write.c:1554
 move_write fs/bcachefs/move.c:217 [inline]
 bch2_moving_ctxt_do_pending_writes+0x5a7/0xe60 fs/bcachefs/move.c:248
 bch2_move_ratelimit+0x8e8/0x1330 fs/bcachefs/move.c:585
 do_rebalance fs/bcachefs/rebalance.c:557 [inline]
 bch2_rebalance_thread+0x17b0/0x1f80 fs/bcachefs/rebalance.c:626
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Modules linked in:
CR2: 0000000000000000
---[ end trace 0000000000000000 ]---
RIP: 0010:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 0018:ffffc9000d49ec18 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffff8880532c75a0
RDX: 1ffff1100a658eb4 RSI: 0000000000000000 RDI: 0000000000092800
RBP: ffffc9000d49ed70 R08: ffffc9000d49ece7 R09: 0000000000000000
R10: ffffc9000d49ecc0 R11: 0000000000000000 R12: 1ffff92001a93d94
R13: ffff8880532c75a0 R14: 0000000000092c40 R15: 0000000000092800
FS:  0000000000000000(0000) GS:ffff88808d20c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000000400eb000 CR4: 0000000000352ef0