The patch titled Subject: reiserfs: don't lock root inode searching has been added to the -mm tree. Its filename is reiserfs-dont-lock-root-inode-searching.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ From: Frederic Weisbecker <fweisbec@xxxxxxxxx> Subject: reiserfs: don't lock root inode searching Nothing requires that we lock the filesystem until the root inode is provided. Also iget5_locked() triggers a warning because we are holding the filesystem lock while allocating the inode, which result in a lockdep suspicion that we have a lock inversion against the reclaim path: [ 1986.896979] ================================= [ 1986.896990] [ INFO: inconsistent lock state ] [ 1986.896997] 3.1.1-main #8 [ 1986.897001] --------------------------------- [ 1986.897007] inconsistent {RECLAIM_FS-ON-W} -> {IN-RECLAIM_FS-W} usage. [ 1986.897016] kswapd0/16 [HC0[0]:SC0[0]:HE1:SE1] takes: [ 1986.897023] (&REISERFS_SB(s)->lock){+.+.?.}, at: [<c01f8bd4>] reiserfs_write_lock+0x20/0x2a [ 1986.897044] {RECLAIM_FS-ON-W} state was registered at: [ 1986.897050] [<c014a5b9>] mark_held_locks+0xae/0xd0 [ 1986.897060] [<c014aab3>] lockdep_trace_alloc+0x7d/0x91 [ 1986.897068] [<c0190ee0>] kmem_cache_alloc+0x1a/0x93 [ 1986.897078] [<c01e7728>] reiserfs_alloc_inode+0x13/0x3d [ 1986.897088] [<c01a5b06>] alloc_inode+0x14/0x5f [ 1986.897097] [<c01a5cb9>] iget5_locked+0x62/0x13a [ 1986.897106] [<c01e99e0>] reiserfs_fill_super+0x410/0x8b9 [ 1986.897114] [<c01953da>] mount_bdev+0x10b/0x159 [ 1986.897123] [<c01e764d>] get_super_block+0x10/0x12 [ 1986.897131] [<c0195b38>] mount_fs+0x59/0x12d [ 1986.897138] [<c01a80d1>] vfs_kern_mount+0x45/0x7a [ 1986.897147] [<c01a83e3>] do_kern_mount+0x2f/0xb0 [ 1986.897155] [<c01a987a>] do_mount+0x5c2/0x612 [ 1986.897163] [<c01a9a72>] sys_mount+0x61/0x8f [ 1986.897170] [<c044060c>] sysenter_do_call+0x12/0x32 [ 1986.897181] irq event stamp: 7509691 [ 1986.897186] hardirqs last enabled at (7509691): [<c0190f34>] kmem_cache_alloc+0x6e/0x93 [ 1986.897197] hardirqs last disabled at (7509690): [<c0190eea>] kmem_cache_alloc+0x24/0x93 [ 1986.897209] softirqs last enabled at (7508896): [<c01294bd>] __do_softirq+0xee/0xfd [ 1986.897222] softirqs last disabled at (7508859): [<c01030ed>] do_softirq+0x50/0x9d [ 1986.897234] [ 1986.897235] other info that might help us debug this: [ 1986.897242] Possible unsafe locking scenario: [ 1986.897244] [ 1986.897250] CPU0 [ 1986.897254] ---- [ 1986.897257] lock(&REISERFS_SB(s)->lock); [ 1986.897265] <Interrupt> [ 1986.897269] lock(&REISERFS_SB(s)->lock); [ 1986.897276] [ 1986.897277] *** DEADLOCK *** [ 1986.897278] [ 1986.897286] no locks held by kswapd0/16. [ 1986.897291] [ 1986.897292] stack backtrace: [ 1986.897299] Pid: 16, comm: kswapd0 Not tainted 3.1.1-main #8 [ 1986.897306] Call Trace: [ 1986.897314] [<c0439e76>] ? printk+0xf/0x11 [ 1986.897324] [<c01482d1>] print_usage_bug+0x20e/0x21a [ 1986.897332] [<c01479b8>] ? print_irq_inversion_bug+0x172/0x172 [ 1986.897341] [<c014855c>] mark_lock+0x27f/0x483 [ 1986.897349] [<c0148d88>] __lock_acquire+0x628/0x1472 [ 1986.897358] [<c0149fae>] lock_acquire+0x47/0x5e [ 1986.897366] [<c01f8bd4>] ? reiserfs_write_lock+0x20/0x2a [ 1986.897384] [<c01f8bd4>] ? reiserfs_write_lock+0x20/0x2a [ 1986.897397] [<c043b5ef>] mutex_lock_nested+0x35/0x26f [ 1986.897409] [<c01f8bd4>] ? reiserfs_write_lock+0x20/0x2a [ 1986.897421] [<c01f8bd4>] reiserfs_write_lock+0x20/0x2a [ 1986.897433] [<c01e2edd>] map_block_for_writepage+0xc9/0x590 [ 1986.897448] [<c01b1706>] ? create_empty_buffers+0x33/0x8f [ 1986.897461] [<c0121124>] ? get_parent_ip+0xb/0x31 [ 1986.897472] [<c043ef7f>] ? sub_preempt_count+0x81/0x8e [ 1986.897485] [<c043cae0>] ? _raw_spin_unlock+0x27/0x3d [ 1986.897496] [<c0121124>] ? get_parent_ip+0xb/0x31 [ 1986.897508] [<c01e355d>] reiserfs_writepage+0x1b9/0x3e7 [ 1986.897521] [<c0173b40>] ? clear_page_dirty_for_io+0xcb/0xde [ 1986.897533] [<c014a6e3>] ? trace_hardirqs_on_caller+0x108/0x138 [ 1986.897546] [<c014a71e>] ? trace_hardirqs_on+0xb/0xd [ 1986.897559] [<c0177b38>] shrink_page_list+0x34f/0x5e2 [ 1986.897572] [<c01780a7>] shrink_inactive_list+0x172/0x22c [ 1986.897585] [<c0178464>] shrink_zone+0x303/0x3b1 [ 1986.897597] [<c043cae0>] ? _raw_spin_unlock+0x27/0x3d [ 1986.897611] [<c01788c9>] kswapd+0x3b7/0x5f2 The deadlock shouldn't happen since we are doing that allocation in the mount path, the filesystem is not available for any reclaim. Still the warning is annoying. To solve this, acquire the lock later only where we need it, right before calling reiserfs_read_locked_inode() that wants to lock to walk the tree. Reported-by: Knut Petersen <Knut_Petersen@xxxxxxxxxxx> Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Christoph Hellwig <hch@xxxxxx> Cc: Jeff Mahoney <jeffm@xxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/reiserfs/super.c | 28 +++++++++++++--------------- 1 file changed, 13 insertions(+), 15 deletions(-) diff -puN fs/reiserfs/super.c~reiserfs-dont-lock-root-inode-searching fs/reiserfs/super.c --- a/fs/reiserfs/super.c~reiserfs-dont-lock-root-inode-searching +++ a/fs/reiserfs/super.c @@ -1428,9 +1428,7 @@ static int read_super_block(struct super static int reread_meta_blocks(struct super_block *s) { ll_rw_block(READ, 1, &(SB_BUFFER_WITH_SB(s))); - reiserfs_write_unlock(s); wait_on_buffer(SB_BUFFER_WITH_SB(s)); - reiserfs_write_lock(s); if (!buffer_uptodate(SB_BUFFER_WITH_SB(s))) { reiserfs_warning(s, "reiserfs-2504", "error reading the super"); return 1; @@ -1738,24 +1736,14 @@ static int reiserfs_fill_super(struct su */ } - /* - * This path assumed to be called with the BKL in the old times. - * Now we have inherited the big reiserfs lock from it and many - * reiserfs helpers called in the mount path and elsewhere require - * this lock to be held even if it's not always necessary. Let's be - * conservative and hold it early. The window can be reduced after - * careful review of the code. - */ - reiserfs_write_lock(s); - if (reread_meta_blocks(s)) { SWARN(silent, s, "jmacd-9", "unable to reread meta blocks after journal init"); - goto error; + goto error_unlocked; } if (replay_only(s)) - goto error; + goto error_unlocked; if (bdev_read_only(s->s_bdev) && !(s->s_flags & MS_RDONLY)) { SWARN(silent, s, "clm-7000", @@ -1769,9 +1757,19 @@ static int reiserfs_fill_super(struct su reiserfs_init_locked_inode, (void *)(&args)); if (!root_inode) { SWARN(silent, s, "jmacd-10", "get root inode failed"); - goto error; + goto error_unlocked; } + /* + * This path assumed to be called with the BKL in the old times. + * Now we have inherited the big reiserfs lock from it and many + * reiserfs helpers called in the mount path and elsewhere require + * this lock to be held even if it's not always necessary. Let's be + * conservative and hold it early. The window can be reduced after + * careful review of the code. + */ + reiserfs_write_lock(s); + if (root_inode->i_state & I_NEW) { reiserfs_read_locked_inode(root_inode, &args); unlock_new_inode(root_inode); _ Subject: Subject: reiserfs: don't lock root inode searching Patches currently in -mm which might be from fweisbec@xxxxxxxxx are linux-next.patch reiserfs-delay-reiserfs-lock-until-journal-initialization.patch reiserfs-dont-lock-journal_init.patch reiserfs-dont-lock-root-inode-searching.patch cgroups-add-res_counter_write_u64-api.patch cgroups-new-resource-counter-inheritance-api.patch cgroups-add-previous-cgroup-in-can_attach_task-attach_task-callbacks.patch cgroups-new-cancel_attach_task-subsystem-callback.patch cgroups-ability-to-stop-res-charge-propagation-on-bounded-ancestor.patch cgroups-add-res-counter-common-ancestor-searching.patch res_counter-allow-charge-failure-pointer-to-be-null.patch cgroups-pull-up-res-counter-charge-failure-interpretation-to-caller.patch cgroups-allow-subsystems-to-cancel-a-fork.patch cgroups-add-a-task-counter-subsystem.patch cgroups-add-a-task-counter-subsystem-fix.patch cgroup-fix-task-counter-common-ancestor-logic.patch cgroup-fix-task-counter-common-ancestor-logic-checkpatch-fixes.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html