Date: Fri, 26 Sep 2008 22:48:03 +1000 From: David Cecil <david.cecil@nokia.com> To: ext Kostik Belousov <kostikbel@gmail.com> Cc: freebsd-fs@freebsd.org Subject: Re: panic in closef Message-ID: <48DCDA03.60702@nokia.com> In-Reply-To: <20080926115631.GT47828@deviant.kiev.zoral.com.ua> References: <48DCC581.80009@nokia.com> <20080926115631.GT47828@deviant.kiev.zoral.com.ua>
next in thread | previous in thread | raw e-mail | index | archive | help
Ah yes, thanks Kostik I looked at that change, it didn't immediately click. After you mentioned it the local variable made sense. Thanks for pointing it out. Dave ext Kostik Belousov wrote: > On Fri, Sep 26, 2008 at 09:20:33PM +1000, David Cecil wrote: > >> Hi, >> >> I'm debugging a panic with the call trace below. This is from a >> 6.1-based kernel, but as far as I can tell there are no fixes for this >> problem in current, based on where I think the problem lies. >> > No, it should be fixed. See > > r168020 | kib | 2007-03-29 11:21:09 +0300 (Thu, 29 Mar 2007) | 7 lines > Extend rev. 1.210 to avoid dereference NULL mp in VFS_NEEDSGIANT and > VFS_ASSERT_GIANT. Stop using reserved namespace. > > and > > r158320 | tegge | 2006-05-05 22:32:35 +0300 (Fri, 05 May 2006) | 2 lines > Avoid dereferencing NULL pointer. > > >> It falls over in the call to VFS_LOCK_GIANT in closef, trying to >> dereference a NULL mount point. To me, the check in VFS_NEEDSGIANT >> looks flawed; it checks that MP isn't NULL, then dereferences it, but >> I'd expect the vnode interlock to be held (or similar), but it isn't >> based on what I see of the code. >> >> I looks to me like vgonel was probably running around the same time. It >> calls delmntque and NULLs v_mount. I can't see how these two threads >> are synchronised to prevent the race condition I describe, but maybe I'm >> missing something. >> >> Any ideas? >> >> Thanks, >> Dave >> >> Unread portion of the kernel message buffer: >> 2 >> panic: page fault >> cpuid = 0 >> KDB: stack backtrace: >> db_trace_self_wrapper(60794d20) at db_trace_self_wrapper+0x25 >> kdb_backtrace(f8d0eae8,100,67aeb640,28,f8d0eb64,...) at kdb_backtrace+0x29 >> panic(60774fbe,607bae69,0,fffff,681dc89b,...) at panic+0x230 >> trap_fatal(f8d0eb64,6f,67aeb640,0,c,...) at trap_fatal+0x2ce >> trap_pfault(f8d0eb64,0,6f) at trap_pfault+0x1ef >> trap(7ae70008,28,f8d00028,3,8236e104,...) at trap+0x36d >> calltrap() at calltrap+0x5 >> --- trap 0xc, eip = 0x60565e72, esp = 0xf8d0eba4, ebp = 0xf8d0ec00 --- >> closef(7d7f19cc,67aeb640) at closef+0x36 >> fdfree(67aeb640) at fdfree+0x5a7 >> exit1(67aeb640,100,f8d0ed30,6074c903,67aeb640,...) at exit1+0x4ee >> exit1(67aeb640,f8d0ed04) at exit1 >> syscall(5fbf003b,812003b,5fbf003b,0,0,...) at syscall+0x2b7 >> Xint0x80_syscall() at Xint0x80_syscall+0x1f >> >> >> _______________________________________________ >> freebsd-fs@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-fs >> To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org" >>
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?48DCDA03.60702>