From: Eric Sandeen <sandeen@redhat.com>
To: fsdevel <linux-fsdevel@vger.kernel.org>
Cc: Jan Kara <jack@suse.cz>, Josef Bacik <jbacik@fb.com>
Subject: [PATCH] fs: avoid softlockups in s_inodes iterators
Date: Fri, 11 Oct 2019 11:49:38 -0500 [thread overview]
Message-ID: <841d0e0f-f04c-9611-2eea-0bcc40e5b084@redhat.com> (raw)
Anything that walks all inodes on sb->s_inodes list without rescheduling
risks softlockups.
Previous efforts were made in 2 functions, see:
c27d82f fs/drop_caches.c: avoid softlockups in drop_pagecache_sb()
ac05fbb inode: don't softlockup when evicting inodes
but there hasn't been an audit of all walkers, so do that now. This
also consistently moves the cond_resched() calls to the bottom of each
loop.
One remains: remove_dquot_ref(), because I'm not quite sure how to deal
with that one w/o taking the i_lock.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---
diff --git a/fs/drop_caches.c b/fs/drop_caches.c
index d31b6c72b476..dc1a1d5d825b 100644
--- a/fs/drop_caches.c
+++ b/fs/drop_caches.c
@@ -35,11 +35,11 @@ static void drop_pagecache_sb(struct super_block *sb, void *unused)
spin_unlock(&inode->i_lock);
spin_unlock(&sb->s_inode_list_lock);
- cond_resched();
invalidate_mapping_pages(inode->i_mapping, 0, -1);
iput(toput_inode);
toput_inode = inode;
+ cond_resched();
spin_lock(&sb->s_inode_list_lock);
}
spin_unlock(&sb->s_inode_list_lock);
diff --git a/fs/inode.c b/fs/inode.c
index fef457a42882..b0c789bb3dba 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -676,6 +676,7 @@ int invalidate_inodes(struct super_block *sb, bool kill_dirty)
struct inode *inode, *next;
LIST_HEAD(dispose);
+again:
spin_lock(&sb->s_inode_list_lock);
list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) {
spin_lock(&inode->i_lock);
@@ -698,6 +699,13 @@ int invalidate_inodes(struct super_block *sb, bool kill_dirty)
inode_lru_list_del(inode);
spin_unlock(&inode->i_lock);
list_add(&inode->i_lru, &dispose);
+
+ if (need_resched()) {
+ spin_unlock(&sb->s_inode_list_lock);
+ cond_resched();
+ dispose_list(&dispose);
+ goto again;
+ }
}
spin_unlock(&sb->s_inode_list_lock);
diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index 2ecef6155fc0..15f77cbbd188 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -67,22 +67,19 @@ static void fsnotify_unmount_inodes(struct super_block *sb)
spin_unlock(&inode->i_lock);
spin_unlock(&sb->s_inode_list_lock);
- if (iput_inode)
- iput(iput_inode);
-
+ iput(iput_inode);
/* for each watch, send FS_UNMOUNT and then remove it */
fsnotify(inode, FS_UNMOUNT, inode, FSNOTIFY_EVENT_INODE, NULL, 0);
-
fsnotify_inode_delete(inode);
iput_inode = inode;
+ cond_resched();
spin_lock(&sb->s_inode_list_lock);
}
spin_unlock(&sb->s_inode_list_lock);
+ iput(iput_inode);
- if (iput_inode)
- iput(iput_inode);
/* Wait for outstanding inode references from connectors */
wait_var_event(&sb->s_fsnotify_inode_refs,
!atomic_long_read(&sb->s_fsnotify_inode_refs));
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 6e826b454082..4a085b3c7cac 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -985,6 +985,7 @@ static int add_dquot_ref(struct super_block *sb, int type)
* later.
*/
old_inode = inode;
+ cond_resched();
spin_lock(&sb->s_inode_list_lock);
}
spin_unlock(&sb->s_inode_list_lock);
next reply other threads:[~2019-10-11 16:49 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-11 16:49 Eric Sandeen [this message]
2019-10-11 17:29 ` [PATCH] fs: avoid softlockups in s_inodes iterators Josef Bacik
2019-10-11 17:34 ` Eric Sandeen
2019-10-11 17:35 ` Josef Bacik
2019-10-11 18:32 ` Matthew Wilcox
2019-10-11 18:45 ` Eric Sandeen
2019-10-11 21:14 ` Eric Sandeen
2019-10-12 4:29 ` Dave Chinner
2019-10-14 8:46 ` Jan Kara
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