Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933351AbaD1WHB (ORCPT ); Mon, 28 Apr 2014 18:07:01 -0400 Received: from mail-pa0-f54.google.com ([209.85.220.54]:52681 "EHLO mail-pa0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932367AbaD1WG7 (ORCPT ); Mon, 28 Apr 2014 18:06:59 -0400 Date: Mon, 28 Apr 2014 15:05:43 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@eggly.anvils To: Linus Torvalds cc: "Srivatsa S. Bhat" , Linux MM , "linux-kernel@vger.kernel.org" , Davidlohr Bueso , Rik van Riel , Michel Lespinasse , "akpm@linux-foundation.org" Subject: Re: [BUG] kernel BUG at mm/vmacache.c:85! In-Reply-To: Message-ID: References: <535EA976.1080402@linux.vnet.ibm.com> User-Agent: Alpine 2.11 (LSU 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 28 Apr 2014, Linus Torvalds wrote: > On Mon, Apr 28, 2014 at 2:20 PM, Linus Torvalds > wrote: > > > > That said, the bug does seem to be that some path doesn't invalidate > > the vmacache sufficiently, or something inserts a vmacache entry into > > the current process when looking up a remote process or whatever. > > Davidlohr, ideas? > > Maybe we missed some use_mm() call. That will change the current mm > without flushing the vma cache. The code considers kernel threads to > be bad targets for vma caching for this reason (and perhaps others), > but maybe we missed something. > > I wonder if we should just invalidate the vma cache in use_mm(), and > remote the "kernel tasks are special" check. > > Srivatsa, are you doing something peculiar on that system that would > trigger this? I see some kdump failures in the log, anything else? I doubt that the vmacache has anything to do with the real problem (though it *might* suggest that vmacache is less robust than what it replaced - maybe). The log is so full of userspace SIGSEGVs and General Protection faults, it looks like userspace was utterly broken by some kernel bug messing up the address space. Hugh -- 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/