FUSE kmemleak report

FUSE kmemleak report

[Sitsofe Wheeler]

Hi,

kmemleak is reporting that 32 bytes are being leaked by FUSE:

unreferenced object 0xe373b270 (size 32):
  comm "fusermount", pid 1207, jiffies 4294707026 (age 2675.187s)
  hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<b05517d7>] kmemleak_alloc+0x27/0x50
    [<b0196435>] kmem_cache_alloc+0xc5/0x180
    [<b02455be>] fuse_alloc_forget+0x1e/0x20
    [<b0245670>] fuse_alloc_inode+0xb0/0xd0
    [<b01b1a8c>] alloc_inode+0x1c/0x80
    [<b01b290f>] iget5_locked+0x8f/0x1a0
    [<b0246022>] fuse_iget+0x72/0x1a0
    [<b02461da>] fuse_get_root_inode+0x8a/0x90
    [<b02465cf>] fuse_fill_super+0x3ef/0x590
    [<b019e56f>] mount_nodev+0x3f/0x90
    [<b0244e95>] fuse_mount+0x15/0x20
    [<b019d1bc>] mount_fs+0x1c/0xc0
    [<b01b5811>] vfs_kern_mount+0x41/0x90
    [<b01b5af9>] do_kern_mount+0x39/0xd0
    [<b01b7585>] do_mount+0x2e5/0x660
    [<b01b7966>] sys_mount+0x66/0xa0

This leak report is consistent and happens once per boot on
3.1.0-rc5-dirty.

-- 
Sitsofe | http://sucs.org/~sits/

Re: FUSE kmemleak report

[Catalin Marinas]

On 5 September 2011 23:37, Sitsofe Wheeler <sitsofe@yahoo.com> wrote:
> kmemleak is reporting that 32 bytes are being leaked by FUSE:
>
> unreferenced object 0xe373b270 (size 32):
>  comm "fusermount", pid 1207, jiffies 4294707026 (age 2675.187s)
>  hex dump (first 32 bytes):
>    01 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00  ................
>    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>  backtrace:
>    [<b05517d7>] kmemleak_alloc+0x27/0x50
>    [<b0196435>] kmem_cache_alloc+0xc5/0x180
>    [<b02455be>] fuse_alloc_forget+0x1e/0x20
>    [<b0245670>] fuse_alloc_inode+0xb0/0xd0
>    [<b01b1a8c>] alloc_inode+0x1c/0x80
>    [<b01b290f>] iget5_locked+0x8f/0x1a0
>    [<b0246022>] fuse_iget+0x72/0x1a0
>    [<b02461da>] fuse_get_root_inode+0x8a/0x90
>    [<b02465cf>] fuse_fill_super+0x3ef/0x590
>    [<b019e56f>] mount_nodev+0x3f/0x90
>    [<b0244e95>] fuse_mount+0x15/0x20
>    [<b019d1bc>] mount_fs+0x1c/0xc0
>    [<b01b5811>] vfs_kern_mount+0x41/0x90
>    [<b01b5af9>] do_kern_mount+0x39/0xd0
>    [<b01b7585>] do_mount+0x2e5/0x660
>    [<b01b7966>] sys_mount+0x66/0xa0
>
> This leak report is consistent and happens once per boot on
> 3.1.0-rc5-dirty.

IIUC, kmemleak reports the fuse_forget_link that corresponds to the
root inode (allocated via fuse_fill_super). The root inode is later
freed (did the mount failed?) but not the forget link. I'm not
familiar with this code, so note exactly sure where the forget link
should have been freed.

-- 
Catalin

Re: FUSE kmemleak report

[Miklos Szeredi]

Catalin Marinas <catalin.marinas@arm.com> writes:

> On 5 September 2011 23:37, Sitsofe Wheeler <sitsofe@yahoo.com> wrote:
>> kmemleak is reporting that 32 bytes are being leaked by FUSE:
>>
>> unreferenced object 0xe373b270 (size 32):
>>  comm "fusermount", pid 1207, jiffies 4294707026 (age 2675.187s)
>>  hex dump (first 32 bytes):
>>    01 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00  ................
>>    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>>  backtrace:
>>    [<b05517d7>] kmemleak_alloc+0x27/0x50
>>    [<b0196435>] kmem_cache_alloc+0xc5/0x180
>>    [<b02455be>] fuse_alloc_forget+0x1e/0x20
>>    [<b0245670>] fuse_alloc_inode+0xb0/0xd0
>>    [<b01b1a8c>] alloc_inode+0x1c/0x80
>>    [<b01b290f>] iget5_locked+0x8f/0x1a0
>>    [<b0246022>] fuse_iget+0x72/0x1a0
>>    [<b02461da>] fuse_get_root_inode+0x8a/0x90
>>    [<b02465cf>] fuse_fill_super+0x3ef/0x590
>>    [<b019e56f>] mount_nodev+0x3f/0x90
>>    [<b0244e95>] fuse_mount+0x15/0x20
>>    [<b019d1bc>] mount_fs+0x1c/0xc0
>>    [<b01b5811>] vfs_kern_mount+0x41/0x90
>>    [<b01b5af9>] do_kern_mount+0x39/0xd0
>>    [<b01b7585>] do_mount+0x2e5/0x660
>>    [<b01b7966>] sys_mount+0x66/0xa0
>>
>> This leak report is consistent and happens once per boot on
>> 3.1.0-rc5-dirty.
>
> IIUC, kmemleak reports the fuse_forget_link that corresponds to the
> root inode (allocated via fuse_fill_super). The root inode is later
> freed (did the mount failed?) but not the forget link. I'm not
> familiar with this code, so note exactly sure where the forget link
> should have been freed.

Sitsofe, thanks for the report.

Could you please try the patch below?

Thanks,
Miklos


diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 168a80f..5cb8614 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -258,10 +258,14 @@ void fuse_queue_forget(struct fuse_conn *fc, struct fuse_forget_link *forget,
 	forget->forget_one.nlookup = nlookup;
 
 	spin_lock(&fc->lock);
-	fc->forget_list_tail->next = forget;
-	fc->forget_list_tail = forget;
-	wake_up(&fc->waitq);
-	kill_fasync(&fc->fasync, SIGIO, POLL_IN);
+	if (fc->connected) {
+		fc->forget_list_tail->next = forget;
+		fc->forget_list_tail = forget;
+		wake_up(&fc->waitq);
+		kill_fasync(&fc->fasync, SIGIO, POLL_IN);
+	} else {
+		kfree(forget);
+	}
 	spin_unlock(&fc->lock);
 }
 

Re: FUSE kmemleak report

[Sitsofe Wheeler]

On Tue, Sep 06, 2011 at 01:43:27PM +0200, Miklos Szeredi wrote:
> 
> Sitsofe, thanks for the report.
> 
> Could you please try the patch below?

You're welcome. The patch resolves the leak for me on 3.1.0-rc5 on
Ubuntu 10.04 using GNOME 2.30.2 (I could previously reproduce it my
logging in as one user, logging out, logging in as another user and then
as root doing echo scan > /sys/kernel/debug/kmemleak ).

Tested-by: Sitsofe Wheeler <sitsofe@yahoo.com>

-- 
Sitsofe | http://sucs.org/~sits/