ext4: init timer earlier to avoid a kernel panic in __save_error_info (04496411) · Commits · 戴 / test

During mount, when we fail to open journal inode or root inode, the __save_error_info will mod_timer. But actually s_err_report isn't initialized yet and the kernel oops. The detailed information can be found https://bugzilla.kernel.org/show_bug.cgi?id=32082 . The best way is to check whether the timer s_err_report is initialized or not. But it seems that in include/linux/timer.h, we can't find a good function to check the status of this timer, so this patch just move the initializtion of s_err_report earlier so that we can avoid the kernel panic. The corresponding del_timer is also added in the error path. Reported-by:

Sami Liedes <sliedes@cc.hut.fi> Signed-off-by:

Tao Ma <boyu.mt@taobao.com> Signed-off-by:

"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/super.c

+5 −3

Original line number	Diff line number	Diff line
		@@ -3391,6 +3391,10 @@ static int ext4_fill_super(struct super_block sb, void data, int silent)
		get_random_bytes(&sbi->s_next_generation, sizeof(u32));
		spin_lock_init(&sbi->s_next_gen_lock);

		init_timer(&sbi->s_err_report);
		sbi->s_err_report.function = print_daily_error_info;
		sbi->s_err_report.data = (unsigned long) sb;

		err = percpu_counter_init(&sbi->s_freeblocks_counter,
		ext4_count_free_blocks(sb));
		if (!err) {
		@@ -3652,9 +3656,6 @@ no_journal:
		"Opts: %s%s%s", descr, sbi->s_es->s_mount_opts,
		*sbi->s_es->s_mount_opts ? "; " : "", orig_data);

		init_timer(&sbi->s_err_report);
		sbi->s_err_report.function = print_daily_error_info;
		sbi->s_err_report.data = (unsigned long) sb;
		if (es->s_error_count)
		mod_timer(&sbi->s_err_report, jiffies + 300HZ); / 5 minutes */

		@@ -3678,6 +3679,7 @@ failed_mount_wq:
		sbi->s_journal = NULL;
		}
		failed_mount3:
		del_timer(&sbi->s_err_report);
		if (sbi->s_flex_groups) {
		if (is_vmalloc_addr(sbi->s_flex_groups))
		vfree(sbi->s_flex_groups);

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