lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20201027135516.336527751@linuxfoundation.org>
Date:   Tue, 27 Oct 2020 14:53:21 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jan Kara <jack@...e.cz>,
        Theodore Tso <tytso@....edu>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.9 551/757] ext4: discard preallocations before releasing group lock

From: Jan Kara <jack@...e.cz>

[ Upstream commit 5b3dc19dda6691e8ab574e8eede1aef6f02a4f1c ]

ext4_mb_discard_group_preallocations() can be releasing group lock with
preallocations accumulated on its local list. Thus although
discard_pa_seq was incremented and concurrent allocating processes will
be retrying allocations, it can happen that premature ENOSPC error is
returned because blocks used for preallocations are not available for
reuse yet. Make sure we always free locally accumulated preallocations
before releasing group lock.

Fixes: 07b5b8e1ac40 ("ext4: mballoc: introduce pcpu seqcnt for freeing PA to improve ENOSPC handling")
Signed-off-by: Jan Kara <jack@...e.cz>
Link: https://lore.kernel.org/r/20200924150959.4335-1-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@....edu>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/ext4/mballoc.c | 33 +++++++++++++--------------------
 1 file changed, 13 insertions(+), 20 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index ff47347012f4b..a8d99f676fb1f 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4160,7 +4160,7 @@ ext4_mb_discard_group_preallocations(struct super_block *sb,
 	struct ext4_buddy e4b;
 	int err;
 	int busy = 0;
-	int free = 0;
+	int free, free_total = 0;
 
 	mb_debug(sb, "discard preallocation for group %u\n", group);
 	if (list_empty(&grp->bb_prealloc_list))
@@ -4188,6 +4188,7 @@ ext4_mb_discard_group_preallocations(struct super_block *sb,
 
 	INIT_LIST_HEAD(&list);
 repeat:
+	free = 0;
 	ext4_lock_group(sb, group);
 	list_for_each_entry_safe(pa, tmp,
 				&grp->bb_prealloc_list, pa_group_list) {
@@ -4217,22 +4218,6 @@ ext4_mb_discard_group_preallocations(struct super_block *sb,
 		list_add(&pa->u.pa_tmp_list, &list);
 	}
 
-	/* if we still need more blocks and some PAs were used, try again */
-	if (free < needed && busy) {
-		busy = 0;
-		ext4_unlock_group(sb, group);
-		cond_resched();
-		goto repeat;
-	}
-
-	/* found anything to free? */
-	if (list_empty(&list)) {
-		BUG_ON(free != 0);
-		mb_debug(sb, "Someone else may have freed PA for this group %u\n",
-			 group);
-		goto out;
-	}
-
 	/* now free all selected PAs */
 	list_for_each_entry_safe(pa, tmp, &list, u.pa_tmp_list) {
 
@@ -4250,14 +4235,22 @@ ext4_mb_discard_group_preallocations(struct super_block *sb,
 		call_rcu(&(pa)->u.pa_rcu, ext4_mb_pa_callback);
 	}
 
-out:
+	free_total += free;
+
+	/* if we still need more blocks and some PAs were used, try again */
+	if (free_total < needed && busy) {
+		ext4_unlock_group(sb, group);
+		cond_resched();
+		busy = 0;
+		goto repeat;
+	}
 	ext4_unlock_group(sb, group);
 	ext4_mb_unload_buddy(&e4b);
 	put_bh(bitmap_bh);
 out_dbg:
 	mb_debug(sb, "discarded (%d) blocks preallocated for group %u bb_free (%d)\n",
-		 free, group, grp->bb_free);
-	return free;
+		 free_total, group, grp->bb_free);
+	return free_total;
 }
 
 /*
-- 
2.25.1



Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ