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Date: Tue, 5 Apr 2011 14:21:39 +0200 Message-ID: Subject: Re: [PATCH] mm: fix possible cause of a page_mapped BUG From: =?UTF-8?B?Um9iZXJ0IMWad2nEmWNraQ==?= To: Hugh Dickins Cc: Linus Torvalds , Andrew Morton , Miklos Szeredi , Michel Lespinasse , "Eric W. Biederman" , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Peter Zijlstra , Rik van Riel Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4995 Lines: 103 >> Hi Hugh, >> >> I did two things, included your patch, and compiled with >> CONFIG_CC_OPTIMIZE_FOR_SIZE=y; the kernel didn't BUG() or Oopssed for >> ~2 days under fuzzing (with getdents and readdir syscalls disabled in >> the fuzzer). I don't think -Os has any bigger influence on how mm >> internally works therefore I must attribute the change to your patch >> (was it patch which fixes something or merely dumps vma structures in >> case of any problem?). > > I'm sorry, I should have explained the patch a little more. Along > with dumping out the vma structs, it does change the BUG or BUGs there > to WARN_ONs, allowing the system to continue if it's not too badly > corrupted, though leaking some structure memory (if the structs have > been reused, it's probably not safe to assume we still have ownership > of them). So if the problem has occurred again, it should be leaving > WARNING messages and vma struct dumps in your /var/log/messages - > please look for them and send them in if found. Here it is, I'll leave it in this state (kdb) in case you need some remote debugging <4>[ 1523.877666] WARNING: at mm/prio_tree.c:95 vma_prio_tree_add+0x43/0x110() <4>[ 1523.884381] Hardware name: Precision WorkStation 390 <4>[ 1523.889703] Pid: 13801, comm: iknowthis2 Not tainted 2.6.38 #2 <4>[ 1523.895544] Call Trace: <4>[ 1523.898000] [] ? warn_slowpath_common+0x7a/0xb0 <4>[ 1523.904195] [] ? warn_slowpath_null+0x1a/0x20 <4>[ 1523.910210] [] ? vma_prio_tree_add+0x43/0x110 <4>[ 1523.916226] [] ? vma_prio_tree_insert+0x41/0x60 <4>[ 1523.922416] [] ? __vma_link_file+0x4c/0x90 <4>[ 1523.928171] [] ? vma_adjust+0xe8/0x570 <4>[ 1523.933579] [] ? __split_vma+0x141/0x280 <4>[ 1523.939157] [] ? split_vma+0x25/0x30 <4>[ 1523.944391] [] ? sys_madvise+0x6a6/0x720 <4>[ 1523.949969] [] ? sub_preempt_count+0xa9/0xe0 <4>[ 1523.955900] [] ? trace_hardirqs_on_thunk+0x3a/0x3c <4>[ 1523.962347] [] ? ia32_sysret+0x0/0x5 <4>[ 1523.967580] [] ? trace_hardirqs_on_thunk+0x3a/0x3c <4>[ 1523.974026] ---[ end trace c13483b7eb481afd ]--- <4>[ 1523.978650] vm_area_struct at ffff880120bda508: <4>[ 1523.983199] ffff88011eb5aa00 00000000f72f3000 00000000f73f0000 ffff88011b8eaa10 <4>[ 1523.990674] ffff88011b8ea228 0000000000000027 00000000000101ff ffff88011b8ea6b1 <4>[ 1523.998151] ffff88011e390820 ffff88011b8ea260 ffff880120796780 ffff880120bdad40 <4>[ 1524.005624] (null) (null) ffff88011ed5b910 ffff88011ed5b1f0 <4>[ 1524.013103] ffff88011f72b168 ffffffff82427480 ffffffffffffff03 ffff8800793ff0c0 <4>[ 1524.020581] (null) (null) (null) <4>[ 1524.026556] vm_area_struct at ffff880120bdacf0: <4>[ 1524.031110] ffff88011eb5a300 00000000f72f3000 00000000f7400000 ffff88011f6c6f18 <4>[ 1524.038584] ffff88011b5c9da8 0000000000000027 00000000000101ff ffff8801206f0c71 <4>[ 1524.046062] ffff88011f6c6f50 ffff88011b5c9de0 ffff880120bdad40 ffff880120bdad40 <4>[ 1524.053536] ffff880120bda558 (null) ffff88011f758ee0 ffff88011f7583a0 <4>[ 1524.061016] ffff88011f556690 ffffffff82427480 ffffffffffffff03 ffff8800793ff0c0 <4>[ 1524.068491] (null) (null) (null) [1]kdb> pid KDB current process is iknowthis2(pid=13801) [1]kdb> btp 13801 Stack traceback for pid 13801 0xffff88011ec35cc0 13801 4516 1 1 R 0xffff88011ec36140 *iknowthis2 ffff88011c5d1d68 0000000000000000 ffff88011f7a3eb8 ffff88011c5d1d88 ffffffff8116b3b9 ffff88011b8ea730 ffff88011b8eaa10 ffff88011c5d1e28 ffffffff8117c0cb 00000000f73f0000 ffff88011eb5aa00 ffff88011f72b168 Call Trace: [] ? vma_prio_tree_remove+0xc9/0x110 [] ? vma_adjust+0x13b/0x570 [] ? __split_vma+0x141/0x280 [] ? split_vma+0x25/0x30 [] ? sys_madvise+0x6a6/0x720 [] ? sub_preempt_count+0xa9/0xe0 [] ? trace_hardirqs_on_thunk+0x3a/0x3c [] ? ia32_sysret+0x0/0x5 [] ? trace_hardirqs_on_thunk+0x3a/0x3c [1]kdb> rd ax: ffff88011b8ea780 bx: ffff880120796678 cx: ffff8801207966c8 dx: ffff8801207966c8 si: ffff8801207966c8 di: ffff880027d3bec8 bp: ffff88011c5d1d68 sp: ffff88011c5d1d68 r8: 0000000000000000 r9: ffff88011c5d1946 r10: ffff88011c5d1945 r11: 0000000000000000 r12: ffff88011b8eaa10 r13: ffff880120bda508 r14: ffff880027d3bea8 r15: ffff88011eb5aa00 ip: ffffffff8158d935 flags: 00010297 cs: 00000010 -- Robert Święcki -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/