>From 9eb3e2f727e1c33ec39c28694a1528b9cc4a32eb Mon Sep 17 00:00:00 2001 From: Pavel Skripkin Date: Thu, 5 Aug 2021 17:23:40 +0300 Subject: [PATCH] ext4: avoid huge mmp update interval value /* .. */ Signed-off-by: Pavel Skripkin --- fs/ext4/mmp.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c index bc364c119af6..2f632344d38c 100644 --- a/fs/ext4/mmp.c +++ b/fs/ext4/mmp.c @@ -7,6 +7,9 @@ #include "ext4.h" +#define EXT4_KMMP_MAX_INTERVAL 100 +#define EXT4_KMMP_MIN_INTERVAL 5 + /* Checksumming functions */ static __le32 ext4_mmp_csum(struct super_block *sb, struct mmp_struct *mmp) { @@ -140,6 +143,11 @@ static int kmmpd(void *data) unsigned long diff; int retval; + /* We should avoid unreasonale huge update interval, since it can cause + * task hung bug on umount or on error handling path in ext4_fill_super() + */ + mmp_update_interval = clamp(mmp_update_interval, EXT4_KMMP_MIN_INTERVAL, EXT4_KMMP_MAX_INTERVAL); + mmp_block = le64_to_cpu(es->s_mmp_block); mmp = (struct mmp_struct *)(bh->b_data); mmp->mmp_time = cpu_to_le64(ktime_get_real_seconds()); @@ -156,6 +164,9 @@ static int kmmpd(void *data) memcpy(mmp->mmp_nodename, init_utsname()->nodename, sizeof(mmp->mmp_nodename)); + ext4_msg(sb, KERN_INFO, "Started kmmp thread with update interval = %u\n", + mmp_update_interval); + while (!kthread_should_stop() && !sb_rdonly(sb)) { if (!ext4_has_feature_mmp(sb)) { ext4_warning(sb, "kmmpd being stopped since MMP feature" -- 2.32.0