From: Vladimir Davydov <vdavydov@virtuozzo.com>
To: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>, <cgroups@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <kernel-team@fb.com>
Subject: Re: [PATCH] memcg: css_alloc should return an ERR_PTR value on error
Date: Wed, 22 Jun 2016 19:44:12 +0300 [thread overview]
Message-ID: <20160622164412.GD21652@esperanza> (raw)
In-Reply-To: <20160621165740.GJ3262@mtj.duckdns.org>
On Tue, Jun 21, 2016 at 12:57:40PM -0400, Tejun Heo wrote:
> mem_cgroup_css_alloc() was returning NULL on failure while cgroup core
> expected it to return an ERR_PTR value leading to the following NULL
> deref after a css allocation failure. Fix it by return
> ERR_PTR(-ENOMEM) instead. I'll also update cgroup core so that it
> can handle NULL returns.
>
> mkdir: page allocation failure: order:6, mode:0x240c0c0(GFP_KERNEL|__GFP_COMP|__GFP_ZERO)
> CPU: 0 PID: 8738 Comm: mkdir Not tainted 4.7.0-rc3+ #123
> ...
> Call Trace:
> [<ffffffff81321937>] dump_stack+0x68/0xa1
> [<ffffffff811522f6>] warn_alloc_failed+0xd6/0x130
> [<ffffffff81152816>] __alloc_pages_nodemask+0x4c6/0xf20
> [<ffffffff8119df86>] alloc_pages_current+0x66/0xe0
> [<ffffffff81153564>] alloc_kmem_pages+0x14/0x80
> [<ffffffff811705ca>] kmalloc_order_trace+0x2a/0x1a0
> [<ffffffff811a7a61>] __kmalloc+0x291/0x310
> [<ffffffff811718dc>] memcg_update_all_caches+0x6c/0x130
> [<ffffffff818d0290>] mem_cgroup_css_alloc+0x590/0x610
> [<ffffffff810f4c7b>] cgroup_apply_control_enable+0x18b/0x370
> [<ffffffff810f8afe>] cgroup_mkdir+0x1de/0x2e0
> [<ffffffff8123cf35>] kernfs_iop_mkdir+0x55/0x80
> [<ffffffff811c6599>] vfs_mkdir+0xb9/0x150
> [<ffffffff811cc666>] SyS_mkdir+0x66/0xd0
> [<ffffffff81002df3>] do_syscall_64+0x53/0x120
> [<ffffffff818d719a>] entry_SYSCALL64_slow_path+0x25/0x25
> ...
> BUG: unable to handle kernel NULL pointer dereference at 00000000000000d0
> IP: [<ffffffff810f2ca7>] init_and_link_css+0x37/0x220
> PGD 34b1e067 PUD 3a109067 PMD 0
> Oops: 0002 [#1] SMP
> Modules linked in:
> CPU: 0 PID: 8738 Comm: mkdir Not tainted 4.7.0-rc3+ #123
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.2-20160422_131301-anatol 04/01/2014
> task: ffff88007cbc5200 ti: ffff8800666d4000 task.ti: ffff8800666d4000
> RIP: 0010:[<ffffffff810f2ca7>] [<ffffffff810f2ca7>] init_and_link_css+0x37/0x220
> RSP: 0018:ffff8800666d7d90 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
> RDX: ffffffff810f2499 RSI: 0000000000000000 RDI: 0000000000000008
> RBP: ffff8800666d7db8 R08: 0000000000000003 R09: 0000000000000000
> R10: 0000000000000001 R11: 0000000000000000 R12: ffff88005a5fb400
> R13: ffffffff81f0f8a0 R14: ffff88005a5fb400 R15: 0000000000000010
> FS: 00007fc944689700(0000) GS:ffff88007fc00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f3aed0d2b80 CR3: 000000003a1e8000 CR4: 00000000000006f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Stack:
> ffffffff81f0f8a0 ffffffff81f0f8a0 ffff88005a5fb400 0000000000000000
> ffff88005a5fb400 ffff8800666d7e18 ffffffff810f4c9c ffff88005a5fb400
> ffffffff82d23470 ffff88007cbc57f0 ffff88007cbc5200 ffff88007d013000
> Call Trace:
> [<ffffffff810f4c9c>] cgroup_apply_control_enable+0x1ac/0x370
> [<ffffffff810f8afe>] cgroup_mkdir+0x1de/0x2e0
> [<ffffffff8123cf35>] kernfs_iop_mkdir+0x55/0x80
> [<ffffffff811c6599>] vfs_mkdir+0xb9/0x150
> [<ffffffff811cc666>] SyS_mkdir+0x66/0xd0
> [<ffffffff81002df3>] do_syscall_64+0x53/0x120
> [<ffffffff818d719a>] entry_SYSCALL64_slow_path+0x25/0x25
> Code: 89 f5 48 89 fb 49 89 d4 48 83 ec 08 8b 05 72 3b d8 00 85 c0 0f 85 60 01 00 00 4c 89 e7 e8 72 f7 ff ff 48 8d 7b 08 48 89 d9 31 c0 <48> c7 83 d0 00 00 00 00 00 00 00 48 83 e7 f8 48 29 f9 81 c1 d8
> RIP [<ffffffff810f2ca7>] init_and_link_css+0x37/0x220
> RSP <ffff8800666d7d90>
> CR2: 00000000000000d0
> ---[ end trace a2d8836ae1e852d1 ]---
>
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Reported-by: Johannes Weiner <hannes@cmpxchg.org>
> Cc: stable@vger.kernel.org
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
> ---
> mm/memcontrol.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 75e7440..fbb8ba6 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -4203,7 +4203,7 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
> return &memcg->css;
> fail:
> mem_cgroup_free(memcg);
> - return NULL;
> + return ERR_PTR(-ENOMEM);
> }
>
> static int
prev parent reply other threads:[~2016-06-22 17:00 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-21 16:57 [PATCH] memcg: css_alloc should return an ERR_PTR value on error Tejun Heo
2016-06-21 17:09 ` Michal Hocko
2016-06-21 18:10 ` Johannes Weiner
2016-06-22 16:44 ` Vladimir Davydov [this message]
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