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Message-ID: <50ED293D.9050605@parallels.com> Date: Wed, 9 Jan 2013 12:24:29 +0400 From: Stanislav Kinsbursky <skinsbursky@...allels.com> To: Sasha Levin <sasha.levin@...cle.com> CC: Andrew Morton <akpm@...ux-foundation.org>, <serge.hallyn@...onical.com>, <ebiederm@...ssion.com>, <linux-kernel@...r.kernel.org>, <xemul@...allels.com>, <catalin.marinas@....com>, <will.deacon@....com>, <jmorris@...ei.org>, <cmetcalf@...era.com>, <joe.korty@...r.com>, <dhowells@...hat.com>, <dledford@...hat.com>, <viro@...iv.linux.org.uk>, <kosaki.motohiro@...fujitsu.com>, <linux-api@...r.kernel.org>, <serue@...ibm.com>, <tglx@...utronix.de>, <paulmck@...ux.vnet.ibm.com>, <devel@...nvz.org>, <mtk.manpages@...il.com>, Wu Fengguang <fengguang.wu@...el.com> Subject: Re: [RFC PATCH v8 0/5] IPC: checkpoint/restore in userspace enhancements 22.12.2012 19:43, Sasha Levin пишет: > On 12/21/2012 04:57 PM, Sasha Levin wrote: >> On 12/21/2012 03:46 PM, Stanislav Kinsbursky wrote: >>> 21.12.2012 00:47, Andrew Morton пишет: >>>> On Thu, 20 Dec 2012 08:06:32 +0400 >>>> Stanislav Kinsbursky<skinsbursky@...allels.com> wrote: >>>> >>>>> 19.12.2012 00:36, Andrew Morton __________: >>>>>> On Wed, 24 Oct 2012 19:34:51 +0400 >>>>>> Stanislav Kinsbursky<skinsbursky@...allels.com> wrote: >>>>>> >>>>>>> This respin of the patch set was significantly reworked. Most part of new API >>>>>>> was replaced by sysctls (by one per messages, semaphores and shared memory), >>>>>>> allowing to preset desired id for next new IPC object. >>>>>>> >>>>>>> This patch set is aimed to provide additional functionality for all IPC >>>>>>> objects, which is required for migration of these objects by user-space >>>>>>> checkpoint/restore utils (CRIU). >>>>>>> >>>>>>> The main problem here was impossibility to set up object id. This patch set >>>>>>> solves the problem by adding new sysctls for preset of desired id for new IPC >>>>>>> object. >>>>>>> >>>>>>> Another problem was to peek messages from queues without deleting them. >>>>>>> This was achived by introducing of new MSG_COPY flag for sys_msgrcv(). If >>>>>>> MSG_COPY flag is set, then msgtyp is interpreted as message number. >>>>>> According to my extensive records, Sasha hit a bug in >>>>>> ipc-message-queue-copy-feature-introduced.patch and Fengguang found a >>>>>> bug in >>>>>> ipc-message-queue-copy-feature-introduced-cleanup-do_msgrcv-aroung-msg_copy-feature.patch >>>>>> >>>>>> It's not obvious (to me) that these things have been identified and >>>>>> fixed. What's the status, please? >>>>> Hello, Andrew. >>>>> Fengguang's issue was solved by "ipc: simplify message copying" I sent you. >>>>> But I can't find Sasha's issue. As I remember, there was some problem in >>>>> early >>>>> version of the patch set. But I believe its fixed now. >>>> http://lkml.indiana.edu/hypermail/linux/kernel/1210.3/01710.html >>>> >>>> Subject: "ipc, msgqueue: NULL ptr deref in msgrcv" >>> >>> Ah, yes. Thanks. >>> Hi found it in initial version of code, which was significantly changed (or cleaned and simplified) by further patch series. >>> And I cant find out, how this can happen, because this patch he bisect to do not modify the queue itself, while he found the >>> problem in testmsg. >> >> I actually can't reproduce it on the latest -next. >> >> I was reverting the IPC changes in the past couple of weeks so that I could test the >> rest of the IPC code with the fuzzer, and when I added them back in again I can't >> reproduce the issue I've reported earlier. >> >> We can probably figure out where it got fixed by bisecting between -next trees if anyone >> is interested in that. > > Ignore that. It just took more fuzzing to stumble on it again: > Hello, Sasha! Thanks! But I still can't understand, how this can happen... And I can't reproduce. Could you specify your load? I.e. how do you stumble on this panic? Looks like you don't use new "copy" feature. > [ 103.164594] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010 > [ 103.168159] IP: [<ffffffff81937155>] do_msgrcv+0x205/0x540 > [ 103.170031] PGD c7cd067 PUD d274067 PMD 0 > [ 103.170031] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC > [ 103.170031] Dumping ftrace buffer: > [ 103.170031] (ftrace buffer empty) > [ 103.170031] CPU 4 > [ 103.170031] Pid: 7056, comm: trinity Tainted: G W 3.7.0-next-20121221-sasha-00014-g339890c #229 > [ 103.170031] RIP: 0010:[<ffffffff81937155>] [<ffffffff81937155>] do_msgrcv+0x205/0x540 > [ 103.170031] RSP: 0018:ffff88000c7cfe88 EFLAGS: 00010246 > [ 103.170031] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 > [ 103.170031] RDX: ffff880013681f00 RSI: 0000000000000124 RDI: ffff8800075a7810 > [ 103.170031] RBP: ffff88000c7cff68 R08: 0000000000000000 R09: 0000000000000000 > [ 103.170031] R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000002 > [ 103.170031] R13: ffff8800075a78c0 R14: 7fffffff00000000 R15: ffff8800075a7810 > [ 103.170031] FS: 00007ffa529ae700(0000) GS:ffff880013c00000(0000) knlGS:0000000000000000 > [ 103.170031] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 103.170031] CR2: 0000000000000010 CR3: 000000000c7cc000 CR4: 00000000000406e0 > [ 103.170031] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 103.170031] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 > [ 103.170031] Process trinity (pid: 7056, threadinfo ffff88000c7ce000, task ffff88000c020000) > [ 103.170031] Stack: > [ 103.170031] ffff88000c7cfea8 ffff88000c020000 ffff88000c020000 ffff88000c020000 > [ 103.170031] 0000000000000000 ffffffff81935e50 0000000000000008 0000000000000000 > [ 103.170031] ffffffff858e91e0 0000000000000000 0000000000001001 ffff88000c020000 > [ 103.170031] Call Trace: > [ 103.170031] [<ffffffff81935e50>] ? load_msg+0x170/0x170 > [ 103.170031] [<ffffffff8107e8c4>] ? syscall_trace_enter+0x24/0x2e0 > [ 103.170031] [<ffffffff81184678>] ? trace_hardirqs_on_caller+0x118/0x140 > [ 103.170031] [<ffffffff819374a0>] sys_msgrcv+0x10/0x20 > [ 103.170031] [<ffffffff83cdf798>] tracesys+0xe1/0xe6 > [ 103.170031] Code: 80 f5 ff ff ff 90 41 83 fc 03 74 32 41 83 fc 04 74 0c 41 83 fc 02 75 2c eb 11 0f 1f 40 00 4c 3b 73 10 7d 20 > 66 90 e9 94 00 00 00 <4c> 39 73 10 0f 85 8a 00 00 00 90 eb 0c 66 0f 1f 44 00 00 4c 39 > [ 103.170031] RIP [<ffffffff81937155>] do_msgrcv+0x205/0x540 > [ 103.170031] RSP <ffff88000c7cfe88> > [ 103.170031] CR2: 0000000000000010 > [ 103.228270] ---[ end trace ddc37199fdad82b0 ]--- > > > Thanks, > Sasha > -- Best regards, Stanislav Kinsbursky -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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