When journal size is set too big by "mkfs.ext4 -J size=", or when
we mount a crafted image to make journal inode->i_size too big,
the loop, "while (i < num)", holds cpu too long. This could cause
soft lockup.
[ 529.357541] Call trace:
[ 529.357551] dump_backtrace+0x0/0x198
[ 529.357555] show_stack+0x24/0x30
[ 529.357562] dump_stack+0xa4/0xcc
[ 529.357568] watchdog_timer_fn+0x300/0x3e8
[ 529.357574] __hrtimer_run_queues+0x114/0x358
[ 529.357576] hrtimer_interrupt+0x104/0x2d8
[ 529.357580] arch_timer_handler_virt+0x38/0x58
[ 529.357584] handle_percpu_devid_irq+0x90/0x248
[ 529.357588] generic_handle_irq+0x34/0x50
[ 529.357590] __handle_domain_irq+0x68/0xc0
[ 529.357593] gic_handle_irq+0x6c/0x150
[ 529.357595] el1_irq+0xb8/0x140
[ 529.357599] __ll_sc_atomic_add_return_acquire+0x14/0x20
[ 529.357668] ext4_map_blocks+0x64/0x5c0 [ext4]
[ 529.357693] ext4_setup_system_zone+0x330/0x458 [ext4]
[ 529.357717] ext4_fill_super+0x2170/0x2ba8 [ext4]
[ 529.357722] mount_bdev+0x1a8/0x1e8
[ 529.357746] ext4_mount+0x44/0x58 [ext4]
[ 529.357748] mount_fs+0x50/0x170
[ 529.357752] vfs_kern_mount.part.9+0x54/0x188
[ 529.357755] do_mount+0x5ac/0xd78
[ 529.357758] ksys_mount+0x9c/0x118
[ 529.357760] __arm64_sys_mount+0x28/0x38
[ 529.357764] el0_svc_common+0x78/0x130
[ 529.357766] el0_svc_handler+0x38/0x78
[ 529.357769] el0_svc+0x8/0xc
[ 541.356516] watchdog: BUG: soft lockup - CPU#0 stuck for 23s! [mount:18674]
Signed-off-by: Shijie Luo <luoshijie1@xxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
---
fs/ext4/block_validity.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
index 1ee04e76bbe0..0a734ffb4310 100644
--- a/fs/ext4/block_validity.c
+++ b/fs/ext4/block_validity.c
@@ -207,6 +207,7 @@ static int ext4_protect_reserved_inode(struct super_block *sb,
return PTR_ERR(inode);
num = (inode->i_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
while (i < num) {
+ cond_resched();
map.m_lblk = i;
map.m_len = num - i;
n = ext4_map_blocks(NULL, inode, &map, 0);
--
2.19.1
