| Message ID | 20191217133319.11861-1-baijiaju1990@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | fs: nfs: fix a possible sleep-in-atomic-context bug in _pnfs_grab_empty_layout() | expand |
On Tue, 2019-12-17 at 21:33 +0800, Jia-Ju Bai wrote: > The filesystem may sleep while holding a spinlock. > The function call path (from bottom to top) in Linux 4.19 is: > > fs/nfs/pnfs.c, 2052: > pnfs_find_alloc_layout(GFP_KERNEL) in _pnfs_grab_empty_layout > fs/nfs/pnfs.c, 2051: > spin_lock in _pnfs_grab_empty_layout > > pnfs_find_alloc_layout(GFP_KERNEL) can sleep at runtime. > > To fix this possible bug, GFP_KERNEL is replaced with GFP_ATOMIC for > pnfs_find_alloc_layout(). > > This bug is found by a static analysis tool STCheck written by > myself. > > Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com> > --- > fs/nfs/pnfs.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c > index cec3070ab577..cfbe170f0651 100644 > --- a/fs/nfs/pnfs.c > +++ b/fs/nfs/pnfs.c > @@ -2138,7 +2138,7 @@ _pnfs_grab_empty_layout(struct inode *ino, > struct nfs_open_context *ctx) > struct pnfs_layout_hdr *lo; > > spin_lock(&ino->i_lock); > - lo = pnfs_find_alloc_layout(ino, ctx, GFP_KERNEL); > + lo = pnfs_find_alloc_layout(ino, ctx, GFP_ATOMIC); > if (!lo) > goto out_unlock; > if (!test_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags)) I'm not seeing why this is necessary. As far as I can see, pnfs_find_alloc_layout() will release the ino->i_lock before sleeping. False positive?
On 2019/12/17 22:37, Trond Myklebust wrote: > On Tue, 2019-12-17 at 21:33 +0800, Jia-Ju Bai wrote: >> The filesystem may sleep while holding a spinlock. >> The function call path (from bottom to top) in Linux 4.19 is: >> >> fs/nfs/pnfs.c, 2052: >> pnfs_find_alloc_layout(GFP_KERNEL) in _pnfs_grab_empty_layout >> fs/nfs/pnfs.c, 2051: >> spin_lock in _pnfs_grab_empty_layout >> >> pnfs_find_alloc_layout(GFP_KERNEL) can sleep at runtime. >> >> To fix this possible bug, GFP_KERNEL is replaced with GFP_ATOMIC for >> pnfs_find_alloc_layout(). >> >> This bug is found by a static analysis tool STCheck written by >> myself. >> >> Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com> >> --- >> fs/nfs/pnfs.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c >> index cec3070ab577..cfbe170f0651 100644 >> --- a/fs/nfs/pnfs.c >> +++ b/fs/nfs/pnfs.c >> @@ -2138,7 +2138,7 @@ _pnfs_grab_empty_layout(struct inode *ino, >> struct nfs_open_context *ctx) >> struct pnfs_layout_hdr *lo; >> >> spin_lock(&ino->i_lock); >> - lo = pnfs_find_alloc_layout(ino, ctx, GFP_KERNEL); >> + lo = pnfs_find_alloc_layout(ino, ctx, GFP_ATOMIC); >> if (!lo) >> goto out_unlock; >> if (!test_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags)) > I'm not seeing why this is necessary. As far as I can see, > pnfs_find_alloc_layout() will release the ino->i_lock before sleeping. > > False positive? > Thanks for the reply. You are right, my report is false... I did not check the definition of pnfs_find_alloc_layout(), sorry... Best wishes, Jia-Ju Bai
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c index cec3070ab577..cfbe170f0651 100644 --- a/fs/nfs/pnfs.c +++ b/fs/nfs/pnfs.c @@ -2138,7 +2138,7 @@ _pnfs_grab_empty_layout(struct inode *ino, struct nfs_open_context *ctx) struct pnfs_layout_hdr *lo; spin_lock(&ino->i_lock); - lo = pnfs_find_alloc_layout(ino, ctx, GFP_KERNEL); + lo = pnfs_find_alloc_layout(ino, ctx, GFP_ATOMIC); if (!lo) goto out_unlock; if (!test_bit(NFS_LAYOUT_INVALID_STID, &lo->plh_flags))
The filesystem may sleep while holding a spinlock. The function call path (from bottom to top) in Linux 4.19 is: fs/nfs/pnfs.c, 2052: pnfs_find_alloc_layout(GFP_KERNEL) in _pnfs_grab_empty_layout fs/nfs/pnfs.c, 2051: spin_lock in _pnfs_grab_empty_layout pnfs_find_alloc_layout(GFP_KERNEL) can sleep at runtime. To fix this possible bug, GFP_KERNEL is replaced with GFP_ATOMIC for pnfs_find_alloc_layout(). This bug is found by a static analysis tool STCheck written by myself. Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com> --- fs/nfs/pnfs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)