On Fri, 2007-07-13 at 02:05 -0700, Andrew Morton wrote:
> On Tue, 10 Jul 2007 16:32:47 -0700 Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> > > + brelse(bh);
> > > + up_write(&EXT4_I(inode)->xattr_sem);
> > > + return error;
> > > +}
> > > +
> >
> > We're doing GFP_KERNEL memory allocations while holding xattr_sem. This
> > can cause the VM to reenter the filesystem, perhaps taking i_mutex and/or
> > i_truncate_sem and/or journal_start() (I forget whether this still
> > happens). Have we checked whether this can occur and if so, whether we are
> > OK from a lock ranking POV? Bear in mind that journalled-data mode is more
> > complex in this regard.
>
> I notice that everyone carefully avoided addressing this ;)
I am not sure why we need GFP_KERNEL flag here. I think we should use
GFP_NOFS instead. The following patch use the GFP_NOFS flag, as well as
fixing memory leak issue introduced by the ext4 expand inode extra isize
patch.
Fixing memory allocation issue with expand inode extra isize patch.
- use GFP_NOFS instead of GFP_KERNEL flag for memory allocation
- use kzalloc instead of kmalloc
- fix memory leak in the success case, at the end of while loop.
Signed-off-by: Mingming Cao <cmm@xxxxxxxxxx>
---
fs/ext4/xattr.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
Index: linux-2.6.22/fs/ext4/xattr.c
===================================================================
--- linux-2.6.22.orig/fs/ext4/xattr.c 2007-07-16 16:12:18.000000000 -0700
+++ linux-2.6.22/fs/ext4/xattr.c 2007-07-16 16:35:59.000000000 -0700
@@ -1204,8 +1204,8 @@ retry:
unsigned int shift_bytes; /* No. of bytes to shift EAs by? */
unsigned int min_total_size = ~0U;
- is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_KERNEL);
- bs = kzalloc(sizeof(struct ext4_xattr_block_find), GFP_KERNEL);
+ is = kzalloc(sizeof(struct ext4_xattr_ibody_find), GFP_NOFS);
+ bs = kzalloc(sizeof(struct ext4_xattr_block_find), GFP_NOFS);
if (!is || !bs) {
error = -ENOMEM;
goto cleanup;
@@ -1251,8 +1251,8 @@ retry:
size = le32_to_cpu(entry->e_value_size);
entry_size = EXT4_XATTR_LEN(entry->e_name_len);
i.name_index = entry->e_name_index,
- buffer = kmalloc(EXT4_XATTR_SIZE(size), GFP_KERNEL);
- b_entry_name = kmalloc(entry->e_name_len + 1, GFP_KERNEL);
+ buffer = kzalloc(EXT4_XATTR_SIZE(size), GFP_NOFS);
+ b_entry_name = kzalloc(entry->e_name_len + 1, GFP_NOFS);
if (!buffer || !b_entry_name) {
error = -ENOMEM;
goto cleanup;
@@ -1302,7 +1302,15 @@ retry:
error = ext4_xattr_block_set(handle, inode, &i, bs);
if (error)
goto cleanup;
+ kfree(b_entry_name);
+ kfree(buffer);
+ brelse(is->iloc.bh);
+ kfree(is);
+ kfree(bs);
+ brelse(bh);
}
+ up_write(&EXT4_I(inode)->xattr_sem);
+ return 0;
cleanup:
kfree(b_entry_name);
-
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