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Date: Thu, 29 Nov 2012 14:06:22 -0800
From: Patrick McLean <patrickm@...kai.com>
To: Al Viro <viro@...iv.linux.org.uk>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: Regression with initramfs and nfsroot (appears to be in the dcache)
On Thu, Nov 29, 2012 at 1:33 PM, Al Viro <viro@...iv.linux.org.uk> wrote:
> On Thu, Nov 29, 2012 at 11:16:59AM -0800, Patrick McLean wrote:
>> With 3.6-rc1 and up, when using a (dracut) initramfs with a read-only
>> nfs root, all accesses to /proc. /sys and /dev return EBUSY.
>
> See "[PATCH] Revert "__d_unalias() should refuse to move mountpoints"
> thread. If you have a convenient reproducer, could you check if
> the fixes the breakage? If so, we'll need to look into false negatives
> from nfs_same_file() in there...
>
> diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
> index ce8cb92..55436f5 100644
> --- a/fs/nfs/dir.c
> +++ b/fs/nfs/dir.c
> @@ -450,7 +450,10 @@ void nfs_prime_dcache(struct dentry *parent, struct nfs_entry *entry)
> nfs_refresh_inode(dentry->d_inode, entry->fattr);
> goto out;
> } else {
> - d_drop(dentry);
> + if (d_invalidate(dentry) != 0) {
> + WARN_ON(1);
> + goto out;
> + }
> dput(dentry);
> }
> }
I have a trivial reproducer and am happy to help debug in any way that
I can. That patch seems to fix the problem, and produces these
warnings in dmesg:
[ 3.306483] dracut: Switching root
[ 4.324378] systemd-udevd[552]: starting version 195
[ 9.254972] ------------[ cut here ]------------
[ 9.254981] WARNING: at fs/nfs/dir.c:454
nfs_readdir_page_filler+0x1cc/0x3a2()
[ 9.254983] Hardware name: Bochs
[ 9.254984] Modules linked in:
[ 9.254989] Pid: 676, comm: ls Not tainted 3.7.0-rc7+ #35
[ 9.254990] Call Trace:
[ 9.254999] [<ffffffff8108534c>] ? warn_slowpath_common+0x76/0x8a
[ 9.255002] [<ffffffff8117de91>] ? nfs_readdir_page_filler+0x1cc/0x3a2
[ 9.255005] [<ffffffff8117e683>] ? nfs_readdir_xdr_to_array+0x1c0/0x22d
[ 9.255009] [<ffffffff8117e70c>] ? nfs_readdir_filler+0x1c/0x6b
[ 9.255014] [<ffffffff810dca9a>] ? add_to_page_cache_lru+0x2c/0x36
[ 9.255017] [<ffffffff8117e6f0>] ? nfs_readdir_xdr_to_array+0x22d/0x22d
[ 9.255020] [<ffffffff810dcbe3>] ? do_read_cache_page+0x7d/0x12b
[ 9.255025] [<ffffffff811274f8>] ? sys_ioctl+0x7a/0x7a
[ 9.255028] [<ffffffff810dccc6>] ? read_cache_page+0x7/0x10
[ 9.255031] [<ffffffff8117e888>] ? nfs_readdir+0x12d/0x435
[ 9.255036] [<ffffffff8118e653>] ? nfs3_xdr_dec_create3res+0xc5/0xc5
[ 9.255039] [<ffffffff811274f8>] ? sys_ioctl+0x7a/0x7a
[ 9.255042] [<ffffffff811274f8>] ? sys_ioctl+0x7a/0x7a
[ 9.255045] [<ffffffff811277b3>] ? vfs_readdir+0x6c/0xa7
[ 9.255049] [<ffffffff811278da>] ? sys_getdents+0x7e/0xdc
[ 9.255053] [<ffffffff814ac769>] ? system_call_fastpath+0x16/0x1b
[ 9.255055] ---[ end trace 5e8b5f37fe752ab1 ]---
[ 9.255062] ------------[ cut here ]------------
[ 9.255065] WARNING: at fs/nfs/dir.c:454
nfs_readdir_page_filler+0x1cc/0x3a2()
[ 9.255066] Hardware name: Bochs
[ 9.255067] Modules linked in:
[ 9.255070] Pid: 676, comm: ls Tainted: G W 3.7.0-rc7+ #35
[ 9.255071] Call Trace:
[ 9.255075] [<ffffffff8108534c>] ? warn_slowpath_common+0x76/0x8a
[ 9.255077] [<ffffffff8117de91>] ? nfs_readdir_page_filler+0x1cc/0x3a2
[ 9.255080] [<ffffffff8117e683>] ? nfs_readdir_xdr_to_array+0x1c0/0x22d
[ 9.255083] [<ffffffff8117e70c>] ? nfs_readdir_filler+0x1c/0x6b
[ 9.255087] [<ffffffff810dca9a>] ? add_to_page_cache_lru+0x2c/0x36
[ 9.255089] [<ffffffff8117e6f0>] ? nfs_readdir_xdr_to_array+0x22d/0x22d
[ 9.255093] [<ffffffff810dcbe3>] ? do_read_cache_page+0x7d/0x12b
[ 9.255096] [<ffffffff811274f8>] ? sys_ioctl+0x7a/0x7a
[ 9.255099] [<ffffffff810dccc6>] ? read_cache_page+0x7/0x10
[ 9.255102] [<ffffffff8117e888>] ? nfs_readdir+0x12d/0x435
[ 9.255105] [<ffffffff8118e653>] ? nfs3_xdr_dec_create3res+0xc5/0xc5
[ 9.255109] [<ffffffff811274f8>] ? sys_ioctl+0x7a/0x7a
[ 9.255112] [<ffffffff811274f8>] ? sys_ioctl+0x7a/0x7a
[ 9.255115] [<ffffffff811277b3>] ? vfs_readdir+0x6c/0xa7
[ 9.255118] [<ffffffff811278da>] ? sys_getdents+0x7e/0xdc
[ 9.255121] [<ffffffff814ac769>] ? system_call_fastpath+0x16/0x1b
[ 9.255122] ---[ end trace 5e8b5f37fe752ab2 ]---
[ 9.255133] ------------[ cut here ]------------
[ 9.255135] WARNING: at fs/nfs/dir.c:454
nfs_readdir_page_filler+0x1cc/0x3a2()
[ 9.255136] Hardware name: Bochs
[ 9.255137] Modules linked in:
[ 9.255140] Pid: 676, comm: ls Tainted: G W 3.7.0-rc7+ #35
[ 9.255141] Call Trace:
[ 9.255144] [<ffffffff8108534c>] ? warn_slowpath_common+0x76/0x8a
[ 9.255147] [<ffffffff8117de91>] ? nfs_readdir_page_filler+0x1cc/0x3a2
[ 9.255150] [<ffffffff8117e683>] ? nfs_readdir_xdr_to_array+0x1c0/0x22d
[ 9.255153] [<ffffffff8117e70c>] ? nfs_readdir_filler+0x1c/0x6b
[ 9.255157] [<ffffffff810dca9a>] ? add_to_page_cache_lru+0x2c/0x36
[ 9.255159] [<ffffffff8117e6f0>] ? nfs_readdir_xdr_to_array+0x22d/0x22d
[ 9.255162] [<ffffffff810dcbe3>] ? do_read_cache_page+0x7d/0x12b
[ 9.255166] [<ffffffff811274f8>] ? sys_ioctl+0x7a/0x7a
[ 9.255169] [<ffffffff810dccc6>] ? read_cache_page+0x7/0x10
[ 9.255171] [<ffffffff8117e888>] ? nfs_readdir+0x12d/0x435
[ 9.255175] [<ffffffff8118e653>] ? nfs3_xdr_dec_create3res+0xc5/0xc5
[ 9.255178] [<ffffffff811274f8>] ? sys_ioctl+0x7a/0x7a
[ 9.255181] [<ffffffff811274f8>] ? sys_ioctl+0x7a/0x7a
[ 9.255184] [<ffffffff811277b3>] ? vfs_readdir+0x6c/0xa7
[ 9.255188] [<ffffffff811278da>] ? sys_getdents+0x7e/0xdc
[ 9.255190] [<ffffffff814ac769>] ? system_call_fastpath+0x16/0x1b
[ 9.255192] ---[ end trace 5e8b5f37fe752ab3 ]---
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