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Message-ID: <20190109020522.105713-1-houtao1@huawei.com>
Date: Wed, 9 Jan 2019 10:05:22 +0800
From: Hou Tao <houtao1@...wei.com>
To: <v9fs-developer@...ts.sourceforge.net>
CC: <asmadeus@...ewreck.org>, <lucho@...kov.net>, <ericvh@...il.com>,
<linux-fsdevel@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<xingaopeng@...wei.com>, <houtao1@...wei.com>
Subject: [PATCH] 9p: use inode->i_lock to protect i_size_write()
Use inode->i_lock to protect i_size_write(), else i_size_read() in
generic_fillattr() may loop infinitely when multiple processes invoke
v9fs_vfs_getattr() or v9fs_vfs_getattr_dotl() simultaneously under
32-bit SMP environment, and a soft lockup will be triggered as show below:
watchdog: BUG: soft lockup - CPU#5 stuck for 22s! [stat:2217]
Modules linked in:
CPU: 5 PID: 2217 Comm: stat Not tainted 5.0.0-rc1-00005-g7f702faf5a9e #4
Hardware name: Generic DT based system
PC is at generic_fillattr+0x104/0x108
LR is at 0xec497f00
pc : [<802b8898>] lr : [<ec497f00>] psr: 200c0013
sp : ec497e20 ip : ed608030 fp : ec497e3c
r10: 00000000 r9 : ec497f00 r8 : ed608030
r7 : ec497ebc r6 : ec497f00 r5 : ee5c1550 r4 : ee005780
r3 : 0000052d r2 : 00000000 r1 : ec497f00 r0 : ed608030
Flags: nzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
Control: 10c5387d Table: ac48006a DAC: 00000051
CPU: 5 PID: 2217 Comm: stat Not tainted 5.0.0-rc1-00005-g7f702faf5a9e #4
Hardware name: Generic DT based system
Backtrace:
[<8010d974>] (dump_backtrace) from [<8010dc88>] (show_stack+0x20/0x24)
[<8010dc68>] (show_stack) from [<80a1d194>] (dump_stack+0xb0/0xdc)
[<80a1d0e4>] (dump_stack) from [<80109f34>] (show_regs+0x1c/0x20)
[<80109f18>] (show_regs) from [<801d0a80>] (watchdog_timer_fn+0x280/0x2f8)
[<801d0800>] (watchdog_timer_fn) from [<80198658>] (__hrtimer_run_queues+0x18c/0x380)
[<801984cc>] (__hrtimer_run_queues) from [<80198e60>] (hrtimer_run_queues+0xb8/0xf0)
[<80198da8>] (hrtimer_run_queues) from [<801973e8>] (run_local_timers+0x28/0x64)
[<801973c0>] (run_local_timers) from [<80197460>] (update_process_times+0x3c/0x6c)
[<80197424>] (update_process_times) from [<801ab2b8>] (tick_nohz_handler+0xe0/0x1bc)
[<801ab1d8>] (tick_nohz_handler) from [<80843050>] (arch_timer_handler_virt+0x38/0x48)
[<80843018>] (arch_timer_handler_virt) from [<80180a64>] (handle_percpu_devid_irq+0x8c/0x240)
[<801809d8>] (handle_percpu_devid_irq) from [<8017ac20>] (generic_handle_irq+0x34/0x44)
[<8017abec>] (generic_handle_irq) from [<8017b344>] (__handle_domain_irq+0x6c/0xc4)
[<8017b2d8>] (__handle_domain_irq) from [<801022e0>] (gic_handle_irq+0x4c/0x88)
[<80102294>] (gic_handle_irq) from [<80101a30>] (__irq_svc+0x70/0x98)
[<802b8794>] (generic_fillattr) from [<8056b284>] (v9fs_vfs_getattr_dotl+0x74/0xa4)
[<8056b210>] (v9fs_vfs_getattr_dotl) from [<802b8904>] (vfs_getattr_nosec+0x68/0x7c)
[<802b889c>] (vfs_getattr_nosec) from [<802b895c>] (vfs_getattr+0x44/0x48)
[<802b8918>] (vfs_getattr) from [<802b8a74>] (vfs_statx+0x9c/0xec)
[<802b89d8>] (vfs_statx) from [<802b9428>] (sys_lstat64+0x48/0x78)
[<802b93e0>] (sys_lstat64) from [<80101000>] (ret_fast_syscall+0x0/0x28)
Reported-by: Xing Gaopeng <xingaopeng@...wei.com>
Signed-off-by: Hou Tao <houtao1@...wei.com>
---
fs/9p/vfs_inode.c | 9 ++++++---
fs/9p/vfs_inode_dotl.c | 9 ++++++---
2 files changed, 12 insertions(+), 6 deletions(-)
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 85ff859d3af5..36405361c2e1 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -1074,6 +1074,7 @@ v9fs_vfs_getattr(const struct path *path, struct kstat *stat,
u32 request_mask, unsigned int flags)
{
struct dentry *dentry = path->dentry;
+ struct inode *inode = d_inode(dentry);
struct v9fs_session_info *v9ses;
struct p9_fid *fid;
struct p9_wstat *st;
@@ -1081,7 +1082,7 @@ v9fs_vfs_getattr(const struct path *path, struct kstat *stat,
p9_debug(P9_DEBUG_VFS, "dentry: %p\n", dentry);
v9ses = v9fs_dentry2v9ses(dentry);
if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
- generic_fillattr(d_inode(dentry), stat);
+ generic_fillattr(inode, stat);
return 0;
}
fid = v9fs_fid_lookup(dentry);
@@ -1092,8 +1093,10 @@ v9fs_vfs_getattr(const struct path *path, struct kstat *stat,
if (IS_ERR(st))
return PTR_ERR(st);
- v9fs_stat2inode(st, d_inode(dentry), dentry->d_sb);
- generic_fillattr(d_inode(dentry), stat);
+ spin_lock(&inode->i_lock);
+ v9fs_stat2inode(st, inode, dentry->d_sb);
+ spin_unlock(&inode->i_lock);
+ generic_fillattr(inode, stat);
p9stat_free(st);
kfree(st);
diff --git a/fs/9p/vfs_inode_dotl.c b/fs/9p/vfs_inode_dotl.c
index 4823e1c46999..ac7d0c9f81c9 100644
--- a/fs/9p/vfs_inode_dotl.c
+++ b/fs/9p/vfs_inode_dotl.c
@@ -474,6 +474,7 @@ v9fs_vfs_getattr_dotl(const struct path *path, struct kstat *stat,
u32 request_mask, unsigned int flags)
{
struct dentry *dentry = path->dentry;
+ struct inode *inode = d_inode(dentry);
struct v9fs_session_info *v9ses;
struct p9_fid *fid;
struct p9_stat_dotl *st;
@@ -481,7 +482,7 @@ v9fs_vfs_getattr_dotl(const struct path *path, struct kstat *stat,
p9_debug(P9_DEBUG_VFS, "dentry: %p\n", dentry);
v9ses = v9fs_dentry2v9ses(dentry);
if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE) {
- generic_fillattr(d_inode(dentry), stat);
+ generic_fillattr(inode, stat);
return 0;
}
fid = v9fs_fid_lookup(dentry);
@@ -496,8 +497,10 @@ v9fs_vfs_getattr_dotl(const struct path *path, struct kstat *stat,
if (IS_ERR(st))
return PTR_ERR(st);
- v9fs_stat2inode_dotl(st, d_inode(dentry));
- generic_fillattr(d_inode(dentry), stat);
+ spin_lock(&inode->i_lock);
+ v9fs_stat2inode_dotl(st, inode);
+ spin_unlock(&inode->i_lock);
+ generic_fillattr(inode, stat);
/* Change block size to what the server returned */
stat->blksize = st->st_blksize;
--
2.16.2.dirty
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