Re: [PATCH] slub: missing test for partial pages flush work in flush_all

[Christoph Lameter <cl@linux.com>]

Didn't I already ack this before?

Acked-by: Christoph Lameter <cl@linux.com>

On Fri, 11 May 2012, majianpeng wrote:

> Subject: [PATCH] slub: missing test for partial pages flush work in flush_all
>
> Find some kernel message like:
> SLUB raid5-md127: kmem_cache_destroy called for cache that still has objects.
> Pid: 6143, comm: mdadm Tainted: G           O 3.4.0-rc6+        #75
> Call Trace:
> [<ffffffff811227f8>] kmem_cache_destroy+0x328/0x400
> [<ffffffffa005ff1d>] free_conf+0x2d/0xf0 [raid456]
> [<ffffffffa0060791>] stop+0x41/0x60 [raid456]
> [<ffffffffa000276a>] md_stop+0x1a/0x60 [md_mod]
> [<ffffffffa000c974>] do_md_stop+0x74/0x470 [md_mod]
> [<ffffffffa000d0ff>] md_ioctl+0xff/0x11f0 [md_mod]
> [<ffffffff8127c958>] blkdev_ioctl+0xd8/0x7a0
> [<ffffffff8115ef6b>] block_ioctl+0x3b/0x40
> [<ffffffff8113b9c6>] do_vfs_ioctl+0x96/0x560
> [<ffffffff8113bf21>] sys_ioctl+0x91/0xa0
> [<ffffffff816e9d22>] system_call_fastpath+0x16/0x1b
>
> Then using kmemleak can found those messages:
> unreferenced object 0xffff8800b6db7380 (size 112):
>   comm "mdadm", pid 5783, jiffies 4294810749 (age 90.589s)
>   hex dump (first 32 bytes):
>     01 01 db b6 ad 4e ad de ff ff ff ff ff ff ff ff  .....N..........
>     ff ff ff ff ff ff ff ff 98 40 4a 82 ff ff ff ff  .........@J.....
>   backtrace:
>     [<ffffffff816b52c1>] kmemleak_alloc+0x21/0x50
>     [<ffffffff8111a11b>] kmem_cache_alloc+0xeb/0x1b0
>     [<ffffffff8111c431>] kmem_cache_open+0x2f1/0x430
>     [<ffffffff8111c6c8>] kmem_cache_create+0x158/0x320
>     [<ffffffffa008f979>] setup_conf+0x649/0x770 [raid456]
>     [<ffffffffa009044b>] run+0x68b/0x840 [raid456]
>     [<ffffffffa000bde9>] md_run+0x529/0x940 [md_mod]
>     [<ffffffffa000c218>] do_md_run+0x18/0xc0 [md_mod]
>     [<ffffffffa000dba8>] md_ioctl+0xba8/0x11f0 [md_mod]
>     [<ffffffff81272b28>] blkdev_ioctl+0xd8/0x7a0
>     [<ffffffff81155bfb>] block_ioctl+0x3b/0x40
>     [<ffffffff811326d6>] do_vfs_ioctl+0x96/0x560
>     [<ffffffff81132c31>] sys_ioctl+0x91/0xa0
>     [<ffffffff816dd3a2>] system_call_fastpath+0x16/0x1b
>     [<ffffffffffffffff>] 0xffffffffffffffff
>
> This bug introduced by Commit a8364d5555b2030d093cde0f0795.The
> commit did not include checks for per cpu partial pages being present on a
> cpu.
>
> Signed-off-by: majianpeng <majianpeng@gmail.com>
> ---
>  mm/slub.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/mm/slub.c b/mm/slub.c
> index ffe13fd..6fce08f 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -2040,7 +2040,7 @@ static bool has_cpu_slab(int cpu, void *info)
>  	struct kmem_cache *s = info;
>  	struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
>
> -	return !!(c->page);
> +	return c->page || c->partial;
>  }
>
>  static void flush_all(struct kmem_cache *s)
>

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