BUG: using smp_processor_id() in preemptible [00000000] code: kworker/u16:3/2181
caller is ext4_mb_new_blocks+0x388/0xed0
CPU: 2 PID: 2181 Comm: kworker/u16:3 Not tainted 5.7.0+ #182
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
Workqueue: writeback wb_workfn (flush-8:0)
Call Trace:
dump_stack+0xb9/0xfc
debug_smp_processor_id+0xc8/0xd0
ext4_mb_new_blocks+0x388/0xed0
ext4_ext_map_blocks+0xa92/0xff0
ext4_map_blocks+0x34e/0x580
ext4_writepages+0xa28/0x11b0
do_writepages+0x46/0xe0
__writeback_single_inode+0x5f/0x6b0
writeback_sb_inodes+0x290/0x620
__writeback_inodes_wb+0x62/0xb0
wb_writeback+0x36c/0x520
wb_workfn+0x319/0x680
process_one_work+0x271/0x640
worker_thread+0x3a/0x3a0
kthread+0x14e/0x170
ret_from_fork+0x27/0x40
Disable preemption before accessing discard_pa_seq.
Fixes: 07b5b8e1ac40 ("ext4: mballoc: introduce pcpu seqcnt for freeing PA to improve ENOSPC handling")
Signed-off-by: YueHaibing <yuehaibing@xxxxxxxxxx>
---
fs/ext4/mballoc.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index a9083113a8c0..30b3bfb1e06a 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4708,7 +4708,8 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle,
}
ac->ac_op = EXT4_MB_HISTORY_PREALLOC;
- seq = *this_cpu_ptr(&discard_pa_seq);
+ seq = *get_cpu_ptr(&discard_pa_seq);
+ put_cpu_ptr(&discard_pa_seq);
if (!ext4_mb_use_preallocated(ac)) {
ac->ac_op = EXT4_MB_HISTORY_ALLOC;
ext4_mb_normalize_request(ac, ar);
--
2.20.1
