From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Filipe Manana <fdmanana@suse.com>,
David Sterba <dsterba@suse.com>, Sasha Levin <sashal@kernel.org>,
clm@fb.com, josef@toxicpanda.com, linux-btrfs@vger.kernel.org
Subject: [PATCH AUTOSEL 5.15 19/39] btrfs: silence lockdep when reading chunk tree during mount
Date: Thu, 25 Nov 2021 21:31:36 -0500 [thread overview]
Message-ID: <20211126023156.441292-19-sashal@kernel.org> (raw)
In-Reply-To: <20211126023156.441292-1-sashal@kernel.org>
From: Filipe Manana <fdmanana@suse.com>
[ Upstream commit 4d9380e0da7be2351437cdac71673a9cd94e50fd ]
Often some test cases like btrfs/161 trigger lockdep splats that complain
about possible unsafe lock scenario due to the fact that during mount,
when reading the chunk tree we end up calling blkdev_get_by_path() while
holding a read lock on a leaf of the chunk tree. That produces a lockdep
splat like the following:
[ 3653.683975] ======================================================
[ 3653.685148] WARNING: possible circular locking dependency detected
[ 3653.686301] 5.15.0-rc7-btrfs-next-103 #1 Not tainted
[ 3653.687239] ------------------------------------------------------
[ 3653.688400] mount/447465 is trying to acquire lock:
[ 3653.689320] ffff8c6b0c76e528 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev.part.0+0xe7/0x320
[ 3653.691054]
but task is already holding lock:
[ 3653.692155] ffff8c6b0a9f39e0 (btrfs-chunk-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x24/0x110 [btrfs]
[ 3653.693978]
which lock already depends on the new lock.
[ 3653.695510]
the existing dependency chain (in reverse order) is:
[ 3653.696915]
-> #3 (btrfs-chunk-00){++++}-{3:3}:
[ 3653.698053] down_read_nested+0x4b/0x140
[ 3653.698893] __btrfs_tree_read_lock+0x24/0x110 [btrfs]
[ 3653.699988] btrfs_read_lock_root_node+0x31/0x40 [btrfs]
[ 3653.701205] btrfs_search_slot+0x537/0xc00 [btrfs]
[ 3653.702234] btrfs_insert_empty_items+0x32/0x70 [btrfs]
[ 3653.703332] btrfs_init_new_device+0x563/0x15b0 [btrfs]
[ 3653.704439] btrfs_ioctl+0x2110/0x3530 [btrfs]
[ 3653.705405] __x64_sys_ioctl+0x83/0xb0
[ 3653.706215] do_syscall_64+0x3b/0xc0
[ 3653.706990] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 3653.708040]
-> #2 (sb_internal#2){.+.+}-{0:0}:
[ 3653.708994] lock_release+0x13d/0x4a0
[ 3653.709533] up_write+0x18/0x160
[ 3653.710017] btrfs_sync_file+0x3f3/0x5b0 [btrfs]
[ 3653.710699] __loop_update_dio+0xbd/0x170 [loop]
[ 3653.711360] lo_ioctl+0x3b1/0x8a0 [loop]
[ 3653.711929] block_ioctl+0x48/0x50
[ 3653.712442] __x64_sys_ioctl+0x83/0xb0
[ 3653.712991] do_syscall_64+0x3b/0xc0
[ 3653.713519] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 3653.714233]
-> #1 (&lo->lo_mutex){+.+.}-{3:3}:
[ 3653.715026] __mutex_lock+0x92/0x900
[ 3653.715648] lo_open+0x28/0x60 [loop]
[ 3653.716275] blkdev_get_whole+0x28/0x90
[ 3653.716867] blkdev_get_by_dev.part.0+0x142/0x320
[ 3653.717537] blkdev_open+0x5e/0xa0
[ 3653.718043] do_dentry_open+0x163/0x390
[ 3653.718604] path_openat+0x3f0/0xa80
[ 3653.719128] do_filp_open+0xa9/0x150
[ 3653.719652] do_sys_openat2+0x97/0x160
[ 3653.720197] __x64_sys_openat+0x54/0x90
[ 3653.720766] do_syscall_64+0x3b/0xc0
[ 3653.721285] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 3653.721986]
-> #0 (&disk->open_mutex){+.+.}-{3:3}:
[ 3653.722775] __lock_acquire+0x130e/0x2210
[ 3653.723348] lock_acquire+0xd7/0x310
[ 3653.723867] __mutex_lock+0x92/0x900
[ 3653.724394] blkdev_get_by_dev.part.0+0xe7/0x320
[ 3653.725041] blkdev_get_by_path+0xb8/0xd0
[ 3653.725614] btrfs_get_bdev_and_sb+0x1b/0xb0 [btrfs]
[ 3653.726332] open_fs_devices+0xd7/0x2c0 [btrfs]
[ 3653.726999] btrfs_read_chunk_tree+0x3ad/0x870 [btrfs]
[ 3653.727739] open_ctree+0xb8e/0x17bf [btrfs]
[ 3653.728384] btrfs_mount_root.cold+0x12/0xde [btrfs]
[ 3653.729130] legacy_get_tree+0x30/0x50
[ 3653.729676] vfs_get_tree+0x28/0xc0
[ 3653.730192] vfs_kern_mount.part.0+0x71/0xb0
[ 3653.730800] btrfs_mount+0x11d/0x3a0 [btrfs]
[ 3653.731427] legacy_get_tree+0x30/0x50
[ 3653.731970] vfs_get_tree+0x28/0xc0
[ 3653.732486] path_mount+0x2d4/0xbe0
[ 3653.732997] __x64_sys_mount+0x103/0x140
[ 3653.733560] do_syscall_64+0x3b/0xc0
[ 3653.734080] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 3653.734782]
other info that might help us debug this:
[ 3653.735784] Chain exists of:
&disk->open_mutex --> sb_internal#2 --> btrfs-chunk-00
[ 3653.737123] Possible unsafe locking scenario:
[ 3653.737865] CPU0 CPU1
[ 3653.738435] ---- ----
[ 3653.739007] lock(btrfs-chunk-00);
[ 3653.739449] lock(sb_internal#2);
[ 3653.740193] lock(btrfs-chunk-00);
[ 3653.740955] lock(&disk->open_mutex);
[ 3653.741431]
*** DEADLOCK ***
[ 3653.742176] 3 locks held by mount/447465:
[ 3653.742739] #0: ffff8c6acf85c0e8 (&type->s_umount_key#44/1){+.+.}-{3:3}, at: alloc_super+0xd5/0x3b0
[ 3653.744114] #1: ffffffffc0b28f70 (uuid_mutex){+.+.}-{3:3}, at: btrfs_read_chunk_tree+0x59/0x870 [btrfs]
[ 3653.745563] #2: ffff8c6b0a9f39e0 (btrfs-chunk-00){++++}-{3:3}, at: __btrfs_tree_read_lock+0x24/0x110 [btrfs]
[ 3653.747066]
stack backtrace:
[ 3653.747723] CPU: 4 PID: 447465 Comm: mount Not tainted 5.15.0-rc7-btrfs-next-103 #1
[ 3653.748873] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
[ 3653.750592] Call Trace:
[ 3653.750967] dump_stack_lvl+0x57/0x72
[ 3653.751526] check_noncircular+0xf3/0x110
[ 3653.752136] ? stack_trace_save+0x4b/0x70
[ 3653.752748] __lock_acquire+0x130e/0x2210
[ 3653.753356] lock_acquire+0xd7/0x310
[ 3653.753898] ? blkdev_get_by_dev.part.0+0xe7/0x320
[ 3653.754596] ? lock_is_held_type+0xe8/0x140
[ 3653.755125] ? blkdev_get_by_dev.part.0+0xe7/0x320
[ 3653.755729] ? blkdev_get_by_dev.part.0+0xe7/0x320
[ 3653.756338] __mutex_lock+0x92/0x900
[ 3653.756794] ? blkdev_get_by_dev.part.0+0xe7/0x320
[ 3653.757400] ? do_raw_spin_unlock+0x4b/0xa0
[ 3653.757930] ? _raw_spin_unlock+0x29/0x40
[ 3653.758437] ? bd_prepare_to_claim+0x129/0x150
[ 3653.758999] ? trace_module_get+0x2b/0xd0
[ 3653.759508] ? try_module_get.part.0+0x50/0x80
[ 3653.760072] blkdev_get_by_dev.part.0+0xe7/0x320
[ 3653.760661] ? devcgroup_check_permission+0xc1/0x1f0
[ 3653.761288] blkdev_get_by_path+0xb8/0xd0
[ 3653.761797] btrfs_get_bdev_and_sb+0x1b/0xb0 [btrfs]
[ 3653.762454] open_fs_devices+0xd7/0x2c0 [btrfs]
[ 3653.763055] ? clone_fs_devices+0x8f/0x170 [btrfs]
[ 3653.763689] btrfs_read_chunk_tree+0x3ad/0x870 [btrfs]
[ 3653.764370] ? kvm_sched_clock_read+0x14/0x40
[ 3653.764922] open_ctree+0xb8e/0x17bf [btrfs]
[ 3653.765493] ? super_setup_bdi_name+0x79/0xd0
[ 3653.766043] btrfs_mount_root.cold+0x12/0xde [btrfs]
[ 3653.766780] ? rcu_read_lock_sched_held+0x3f/0x80
[ 3653.767488] ? kfree+0x1f2/0x3c0
[ 3653.767979] legacy_get_tree+0x30/0x50
[ 3653.768548] vfs_get_tree+0x28/0xc0
[ 3653.769076] vfs_kern_mount.part.0+0x71/0xb0
[ 3653.769718] btrfs_mount+0x11d/0x3a0 [btrfs]
[ 3653.770381] ? rcu_read_lock_sched_held+0x3f/0x80
[ 3653.771086] ? kfree+0x1f2/0x3c0
[ 3653.771574] legacy_get_tree+0x30/0x50
[ 3653.772136] vfs_get_tree+0x28/0xc0
[ 3653.772673] path_mount+0x2d4/0xbe0
[ 3653.773201] __x64_sys_mount+0x103/0x140
[ 3653.773793] do_syscall_64+0x3b/0xc0
[ 3653.774333] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 3653.775094] RIP: 0033:0x7f648bc45aaa
This happens because through btrfs_read_chunk_tree(), which is called only
during mount, ends up acquiring the mutex open_mutex of a block device
while holding a read lock on a leaf of the chunk tree while other paths
need to acquire other locks before locking extent buffers of the chunk
tree.
Since at mount time when we call btrfs_read_chunk_tree() we know that
we don't have other tasks running in parallel and modifying the chunk
tree, we can simply skip locking of chunk tree extent buffers. So do
that and move the assertion that checks the fs is not yet mounted to the
top block of btrfs_read_chunk_tree(), with a comment before doing it.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/btrfs/volumes.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 6afebc5b10c84..8ad62d9fbb0ad 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -7483,6 +7483,19 @@ int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info)
*/
fs_info->fs_devices->total_rw_bytes = 0;
+ /*
+ * Lockdep complains about possible circular locking dependency between
+ * a disk's open_mutex (struct gendisk.open_mutex), the rw semaphores
+ * used for freeze procection of a fs (struct super_block.s_writers),
+ * which we take when starting a transaction, and extent buffers of the
+ * chunk tree if we call read_one_dev() while holding a lock on an
+ * extent buffer of the chunk tree. Since we are mounting the filesystem
+ * and at this point there can't be any concurrent task modifying the
+ * chunk tree, to keep it simple, just skip locking on the chunk tree.
+ */
+ ASSERT(!test_bit(BTRFS_FS_OPEN, &fs_info->flags));
+ path->skip_locking = 1;
+
/*
* Read all device items, and then all the chunk items. All
* device items are found before any chunk item (their object id
@@ -7508,10 +7521,6 @@ int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info)
goto error;
break;
}
- /*
- * The nodes on level 1 are not locked but we don't need to do
- * that during mount time as nothing else can access the tree
- */
node = path->nodes[1];
if (node) {
if (last_ra_node != node->start) {
@@ -7539,7 +7548,6 @@ int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info)
* requirement for chunk allocation, see the comment on
* top of btrfs_chunk_alloc() for details.
*/
- ASSERT(!test_bit(BTRFS_FS_OPEN, &fs_info->flags));
chunk = btrfs_item_ptr(leaf, slot, struct btrfs_chunk);
ret = read_one_chunk(&found_key, leaf, chunk);
if (ret)
--
2.33.0
next prev parent reply other threads:[~2021-11-26 2:35 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-26 2:31 [PATCH AUTOSEL 5.15 01/39] gfs2: release iopen glock early in evict Sasha Levin
2021-11-26 2:31 ` [Cluster-devel] " Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 02/39] gfs2: Fix length of holes reported at end-of-file Sasha Levin
2021-11-26 2:31 ` [Cluster-devel] " Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 03/39] powerpc/pseries/ddw: Revert "Extend upper limit for huge DMA window for persistent memory" Sasha Levin
2021-11-26 2:31 ` Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 04/39] powerpc/pseries/ddw: Do not try direct mapping with persistent memory and one window Sasha Levin
2021-11-26 2:31 ` Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 05/39] drm/sun4i: fix unmet dependency on RESET_CONTROLLER for PHY_SUN6I_MIPI_DPHY Sasha Levin
2021-11-26 2:31 ` Sasha Levin
2021-11-26 2:31 ` Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 06/39] mac80211: do not access the IV when it was stripped Sasha Levin
2021-11-26 2:31 ` Sasha Levin
2021-11-26 2:31 ` Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 07/39] mac80211: fix throughput LED trigger Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 08/39] x86/hyperv: Move required MSRs check to initial platform probing Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 09/39] tun: fix bonding active backup with arp monitoring Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 10/39] net/smc: Transfer remaining wait queue entries during fallback Sasha Levin
2021-11-26 2:51 ` Jakub Kicinski
2021-12-03 18:20 ` Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 11/39] atlantic: Fix OOB read and write in hw_atl_utils_fw_rpc_wait Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 12/39] net: return correct error code Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 13/39] pinctrl: qcom: fix unmet dependencies on GPIOLIB for GPIOLIB_IRQCHIP Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 14/39] blk-mq: cancel blk-mq dispatch work in both blk_cleanup_queue and disk_release() Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 15/39] platform/x86: dell-wmi-descriptor: disable by default Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 16/39] platform/x86: thinkpad_acpi: Add support for dual fan control Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 17/39] platform/x86: thinkpad_acpi: Fix WWAN device disabled issue after S3 deep Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 18/39] s390/setup: avoid using memblock_enforce_memory_limit Sasha Levin
2021-11-26 2:31 ` Sasha Levin [this message]
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 20/39] btrfs: check-integrity: fix a warning on write caching disabled disk Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 21/39] thermal: core: Reset previous low and high trip during thermal zone init Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 22/39] scsi: iscsi: Unblock session then wake up error handler Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 23/39] net: usb: r8152: Add MAC passthrough support for more Lenovo Docks Sasha Levin
2021-11-28 9:49 ` Sergey Shtylyov
2021-11-28 9:50 ` Sergey Shtylyov
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 24/39] drm/amd/pm: Remove artificial freq level on Navi1x Sasha Levin
2021-11-26 2:31 ` Sasha Levin
2021-11-26 2:31 ` Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 25/39] drm/amd/amdkfd: Fix kernel panic when reset failed and been triggered again Sasha Levin
2021-11-26 2:31 ` Sasha Levin
2021-11-26 2:31 ` Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 26/39] drm/amd/amdgpu: fix potential memleak Sasha Levin
2021-11-26 2:31 ` Sasha Levin
2021-11-26 2:31 ` Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 27/39] ata: ahci: Add Green Sardine vendor ID as board_ahci_mobile Sasha Levin
2021-11-29 14:46 ` Limonciello, Mario
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 28/39] ata: libahci: Adjust behavior when StorageD3Enable _DSD is set Sasha Levin
2021-11-29 14:46 ` Limonciello, Mario
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 29/39] ethernet: hisilicon: hns: hns_dsaf_misc: fix a possible array overflow in hns_dsaf_ge_srst_by_port() Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 30/39] ipv6: check return value of ipv6_skip_exthdr Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 31/39] net: tulip: de4x5: fix the problem that the array 'lp->phy[8]' may be out of bound Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 32/39] net: ethernet: dec: tulip: de4x5: fix possible array overflows in type3_infoblock() Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 33/39] perf sort: Fix the 'weight' sort key behavior Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 34/39] perf sort: Fix the 'ins_lat' " Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 35/39] perf sort: Fix the 'p_stage_cyc' " Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 36/39] perf inject: Fix ARM SPE handling Sasha Levin
2021-11-26 2:31 ` Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 37/39] perf hist: Fix memory leak of a perf_hpp_fmt Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 38/39] perf report: Fix memory leaks around perf_tip() Sasha Levin
2021-11-26 2:31 ` [PATCH AUTOSEL 5.15 39/39] tracing: Don't use out-of-sync va_list in event printing Sasha Levin
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