On 11/22/10 12:02 AM, [email protected] wrote:
> From: Zeng Zhaoming<[email protected]>
>
> please check the discuss with allocator guys.
> http://marc.info/?l=linux-kernel&m=129004890020256&w=2
>
> Get a memory leak about ext4:
> comm "mount", pid 1159, jiffies 4294904647 (age 6077.804s)
> hex dump (first 32 bytes):
> 65 78 74 34 5f 67 72 6f 75 70 69 6e 66 6f 5f 31 ext4_groupinfo_1
> 30 00 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5 0.kkkkkkkkkkkkk.
> backtrace:
> [<c068ade3>] kmemleak_alloc+0x93/0xd0
> [<c024e54c>] __kmalloc_track_caller+0x30c/0x380
> [<c02269d3>] kstrdup+0x33/0x60
> [<c0318a70>] ext4_mb_init+0x4e0/0x550
> [<c0304e0e>] ext4_fill_super+0x1e6e/0x2f60
> [<c0261140>] mount_bdev+0x1c0/0x1f0
> [<c02fc00f>] ext4_mount+0x1f/0x30
> [<c02603d8>] vfs_kern_mount+0x78/0x250
> [<c026060e>] do_kern_mount+0x3e/0x100
> [<c027b4c2>] do_mount+0x2e2/0x780
> [<c027ba04>] sys_mount+0xa4/0xd0
> [<c010429f>] sysenter_do_call+0x12/0x38
> [<ffffffff>] 0xffffffff
>
> ext4 allocate memory for cache name by:
> namep = kstrdup(name, GFP_KERNEL);
> and reclaim it by:
> name = kmem_cache_name(cache);
> kfree(name)
>
> This is ok if allocator only reference to the cache name memory, and return
> the name memory pass to kmem_cache_create() by kmem_cache_name();
> But not true in slub, when using slub, memory leak and double free error appears.
>
> In this patch, we track the cache name memory in ext4, rather than allocator.
>
> Signed-off-by: Zeng Zhaoming<[email protected]>
> ---
Hmm. Maybe it's better to change SLAB and SLOB to do kstrdup()
internally so we can drop it from ext4 code. Matt, are you OK with that?
Pekka
On Mon, 2010-11-22 at 08:47 +0200, Pekka Enberg wrote:
> On 11/22/10 12:02 AM, [email protected] wrote:
> > From: Zeng Zhaoming<[email protected]>
> >
> > please check the discuss with allocator guys.
> > http://marc.info/?l=linux-kernel&m=129004890020256&w=2
> >
> > Get a memory leak about ext4:
> > comm "mount", pid 1159, jiffies 4294904647 (age 6077.804s)
> > hex dump (first 32 bytes):
> > 65 78 74 34 5f 67 72 6f 75 70 69 6e 66 6f 5f 31 ext4_groupinfo_1
> > 30 00 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5 0.kkkkkkkkkkkkk.
> > backtrace:
> > [<c068ade3>] kmemleak_alloc+0x93/0xd0
> > [<c024e54c>] __kmalloc_track_caller+0x30c/0x380
> > [<c02269d3>] kstrdup+0x33/0x60
> > [<c0318a70>] ext4_mb_init+0x4e0/0x550
> > [<c0304e0e>] ext4_fill_super+0x1e6e/0x2f60
> > [<c0261140>] mount_bdev+0x1c0/0x1f0
> > [<c02fc00f>] ext4_mount+0x1f/0x30
> > [<c02603d8>] vfs_kern_mount+0x78/0x250
> > [<c026060e>] do_kern_mount+0x3e/0x100
> > [<c027b4c2>] do_mount+0x2e2/0x780
> > [<c027ba04>] sys_mount+0xa4/0xd0
> > [<c010429f>] sysenter_do_call+0x12/0x38
> > [<ffffffff>] 0xffffffff
> >
> > ext4 allocate memory for cache name by:
> > namep = kstrdup(name, GFP_KERNEL);
> > and reclaim it by:
> > name = kmem_cache_name(cache);
> > kfree(name)
> >
> > This is ok if allocator only reference to the cache name memory, and return
> > the name memory pass to kmem_cache_create() by kmem_cache_name();
> > But not true in slub, when using slub, memory leak and double free error appears.
> >
> > In this patch, we track the cache name memory in ext4, rather than allocator.
> >
> > Signed-off-by: Zeng Zhaoming<[email protected]>
> > ---
>
> Hmm. Maybe it's better to change SLAB and SLOB to do kstrdup()
> internally so we can drop it from ext4 code. Matt, are you OK with that?
If we drop the kmem_cache_name interface, then SLOB can drop tracking
the name entirely.
--
Mathematics is the supreme nostalgia of our time.