Date: Sun, 20 May 2012 17:23:33 +0400 From: Andrey Zonov <andrey@zonov.org> To: freebsd-stable <freebsd-stable@freebsd.org> Cc: Mateusz Guzik <mjguzik@gmail.com>, trasz@freebsd.org Subject: Re: panic with overcommit and RACCT Message-ID: <4FB8F055.9080700@zonov.org> In-Reply-To: <4FB177EE.7030808@zonov.org> References: <4FAFEEEF.3040706@zonov.org> <20120513202920.GA18238@dft-labs.eu> <4FB177EE.7030808@zonov.org>
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On 5/15/12 1:23 AM, Andrey Zonov wrote: > On 5/14/12 12:29 AM, Mateusz Guzik wrote: >> On Sun, May 13, 2012 at 09:27:11PM +0400, Andrey Zonov wrote: >>> Hi, >>> >>> I've got a repeatable panic on latest 9.0-STABLE and HEAD with >>> turned on overcommit (vm.overcommit=1) and RACCT. >>> >>> kgdb trace on today's HEAD: >>> >>> #10 0xffffffff80bc3513 in calltrap () >>> at /usr/src/sys/amd64/amd64/exception.S:228 >>> #11 0xffffffff808aab71 in racct_set_locked (p=0xfffffe0005d684a0, >>> resource=0, >>> amount=2680) at /usr/src/sys/kern/kern_racct.c:372 >>> #12 0xffffffff808ab645 in racct_proc_exit (p=0xfffffe0005d684a0) >>> at /usr/src/sys/kern/kern_racct.c:615 >>> #13 0xffffffff80880d69 in fork1 (td=0xfffffe0005b2c460, flags=20, >>> pages=4, >>> procp=0xffffff811a36bb00, procdescp=Variable "procdescp" is not >>> available. >>> ) at /usr/src/sys/kern/kern_fork.c:943 >>> #14 0xffffffff80882362 in sys_fork (td=0xfffffe0005b2c460, >>> uap=Variable "uap" is not available. >>> ) >>> at /usr/src/sys/kern/kern_fork.c:110 >>> #15 0xffffffff80bd7a89 in amd64_syscall (td=0xfffffe0005b2c460, >>> traced=0) >>> at subr_syscall.c:135 >>> #16 0xffffffff80bc37f7 in Xfast_syscall () >>> at /usr/src/sys/amd64/amd64/exception.S:387 >>> #17 0x00000008024729fc in ?? () >>> Previous frame inner to this frame (corrupt stack?) >>> (kgdb) >>> >>> Unread portion of the kernel message buffer: >>> Kernel page fault with the following non-sleepable locks held: >>> exclusive sleep mutex racct lock (racct lock) r = 0 >>> (0xffffffff8128a7c0) locked @ /usr/src/sys/kern/kern_racct.c:614 >>> exclusive sleep mutex process lock (process lock) r = 0 >>> (0xfffffe0005d68598) locked @ /usr/src/sys/kern/kern_racct.c:603 >>> >> >> It looks like racct_proc_exit can be called for processes without >> properly initialized racct structure, which in turn results in this >> panic. >> >> Can you please test this patch: >> http://student.agh.edu.pl/~mjguzik/patches/racct-fork.patch >> >> ? >> >> I was unable to reproduce panic you describe, so it was tested only by >> manually injecting error. Nevertheless I think you should try it. :) >> > > Thanks, your patch fixes the panic. Can anyone commit this fix? > > How to repeat: > 1. add options RACCT and options RCTL to kernel config, rebuild and > install kernel, reboot > 2. set sysctl vm.overcommit=1 > 3. run as none root something that eats memory (I just run malloc() > until it returns NULL) > 4. swapoff -a > 5. panic after sometime > > With patch applied instead of panic I got: "fork: Cannot allocate > memory". Looks like a bug in overcommit code. > -- Andrey Zonov
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