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  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Date:	Sun, 02 Nov 2014 08:31:18 +0100
From:	Mike Galbraith <>
To:	Steven Rostedt <>
Cc:	LKML <>,
	linux-rt-users <>,
	Thomas Gleixner <>,
	Carsten Emde <>,
	John Kacur <>,
	Sebastian Andrzej Siewior <>,
	Clark Williams <>
Subject: 3.14.23-rt20 - fs,btrfs: fix rt deadlock on extent_buffer->lock

Subject: fs,btrfs: fix rt deadlock on extent_buffer->lock
From: Mike Galbraith <>
Sat Jul 14 12:30:41 CEST 2012

Trivially repeatable deadlock is cured by enabling lockdep code in
btrfs_clear_path_blocking() as suggested by Chris Mason.  He also
suggested restricting blocking reader count to one, and not allowing
a spinning reader while blocking reader exists.  This has proven to
be unnecessary, the strict lock order enforcement is enough.. or
rather that's my box's opinion after long hours of hard pounding.

Note: extent-tree.c bit is additional recommendation from Chris
      Mason, split into a separate patch after discussion.

Signed-off-by: Mike Galbraith <>
Cc: Chris Mason <>
 fs/btrfs/ctree.c       |    4 ++--
 fs/btrfs/extent-tree.c |    8 --------
 2 files changed, 2 insertions(+), 10 deletions(-)

--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -80,7 +80,7 @@ noinline void btrfs_clear_path_blocking(
 	int i;
 	/* lockdep really cares that we take all of these spinlocks
 	 * in the right order.  If any of the locks in the path are not
 	 * currently blocking, it is going to complain.  So, make really
@@ -107,7 +107,7 @@ noinline void btrfs_clear_path_blocking(
 	if (held)
 		btrfs_clear_lock_blocking_rw(held, held_rw);
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -6938,14 +6938,6 @@ use_block_rsv(struct btrfs_trans_handle
 		goto again;
-	if (btrfs_test_opt(root, ENOSPC_DEBUG)) {
-		if (__ratelimit(&_rs))
-				"BTRFS: block rsv returned %d\n", ret);
-	}
 	ret = reserve_metadata_bytes(root, block_rsv, blocksize,

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

Powered by blists - more mailing lists