On Mon, 2010-11-22 at 08:47 +0200, Pekka Enberg wrote: > On 11/22/10 12:02 AM, zeng.zhaoming@xxxxxxxxxxxxx wrote: > > From: Zeng Zhaoming<zengzm.kernel@xxxxxxxxx> > > > > 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<zengzm.kernel@xxxxxxxxx> > > --- > > 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. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
