Re: kernel panic on null pointer on page->mem_cgroup

2017-08-21 Thread Michal Hocko
On Mon 21-08-17 09:02:18, Johannes Weiner wrote: > On Thu, Aug 10, 2017 at 01:56:05PM +0200, Michal Hocko wrote: > > On Wed 09-08-17 14:38:25, Johannes Weiner wrote: > > > The issue is that writeback doesn't hold a page reference and the page > > > might get freed after PG_writeback is cleared (and

Re: kernel panic on null pointer on page->mem_cgroup

2017-08-21 Thread Johannes Weiner
On Thu, Aug 10, 2017 at 01:56:05PM +0200, Michal Hocko wrote: > On Wed 09-08-17 14:38:25, Johannes Weiner wrote: > > The issue is that writeback doesn't hold a page reference and the page > > might get freed after PG_writeback is cleared (and the mapping is > > unlocked) in test_clear_page_writebac

Re: kernel panic on null pointer on page->mem_cgroup

2017-08-11 Thread Jaegeuk Kim
Hi Johannes, On 08/09, Johannes Weiner wrote: > On Tue, Aug 08, 2017 at 10:39:27PM -0400, Brad Bolen wrote: > > Yes, the BUG_ON(!page_count(page)) fired for me as well. > > Brad, Jaegeuk, does the following patch address this problem? I also confirmed that this patch addresses the problem. Test

Re: kernel panic on null pointer on page->mem_cgroup

2017-08-10 Thread Brad Bolen
Johannes, Yes, the patch (slightly modified to apply for 4.11) does make my problem go away. Thank you for driving this to a solution. Brad On Wed, Aug 9, 2017 at 2:38 PM, Johannes Weiner wrote: > On Tue, Aug 08, 2017 at 10:39:27PM -0400, Brad Bolen wrote: >> Yes, the BUG_ON(!page_count(page))

Re: kernel panic on null pointer on page->mem_cgroup

2017-08-10 Thread Michal Hocko
On Wed 09-08-17 14:38:25, Johannes Weiner wrote: > On Tue, Aug 08, 2017 at 10:39:27PM -0400, Brad Bolen wrote: > > Yes, the BUG_ON(!page_count(page)) fired for me as well. > > Brad, Jaegeuk, does the following patch address this problem? > > --- > > >From cf0060892eb70bccbc8cedeac0a5756c8f7b975e

Re: kernel panic on null pointer on page->mem_cgroup

2017-08-09 Thread Johannes Weiner
On Tue, Aug 08, 2017 at 10:39:27PM -0400, Brad Bolen wrote: > Yes, the BUG_ON(!page_count(page)) fired for me as well. Brad, Jaegeuk, does the following patch address this problem? --- >From cf0060892eb70bccbc8cedeac0a5756c8f7b975e Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Wed, 9 Aug

Re: kernel panic on null pointer on page->mem_cgroup

2017-08-08 Thread Brad Bolen
Yes, the BUG_ON(!page_count(page)) fired for me as well. On Tue, Aug 8, 2017 at 9:44 PM, Jaegeuk Kim wrote: > On 08/08, Johannes Weiner wrote: >> On Tue, Aug 08, 2017 at 03:13:42PM -0400, Brad Bolen wrote: >> > On Tue, Aug 8, 2017 at 1:37 PM, Johannes Weiner wrote: >> > > On Tue, Aug 08, 2017 at

Re: kernel panic on null pointer on page->mem_cgroup

2017-08-08 Thread Jaegeuk Kim
On 08/08, Johannes Weiner wrote: > On Tue, Aug 08, 2017 at 03:13:42PM -0400, Brad Bolen wrote: > > On Tue, Aug 8, 2017 at 1:37 PM, Johannes Weiner wrote: > > > On Tue, Aug 08, 2017 at 09:56:01AM -0700, Jaegeuk Kim wrote: > > >> On 08/08, Johannes Weiner wrote: > > >> > Hi Jaegeuk and Bradley, > >

Re: kernel panic on null pointer on page->mem_cgroup

2017-08-08 Thread Johannes Weiner
On Tue, Aug 08, 2017 at 03:13:42PM -0400, Brad Bolen wrote: > On Tue, Aug 8, 2017 at 1:37 PM, Johannes Weiner wrote: > > On Tue, Aug 08, 2017 at 09:56:01AM -0700, Jaegeuk Kim wrote: > >> On 08/08, Johannes Weiner wrote: > >> > Hi Jaegeuk and Bradley, > >> > > >> > On Mon, Aug 07, 2017 at 09:01:50P

Re: kernel panic on null pointer on page->mem_cgroup

2017-08-08 Thread Brad Bolen
On Tue, Aug 8, 2017 at 1:37 PM, Johannes Weiner wrote: > On Tue, Aug 08, 2017 at 09:56:01AM -0700, Jaegeuk Kim wrote: >> On 08/08, Johannes Weiner wrote: >> > Hi Jaegeuk and Bradley, >> > >> > On Mon, Aug 07, 2017 at 09:01:50PM -0400, Bradley Bolen wrote: >> > > I am getting a very similar error o

Re: kernel panic on null pointer on page->mem_cgroup

2017-08-08 Thread Johannes Weiner
On Tue, Aug 08, 2017 at 09:56:01AM -0700, Jaegeuk Kim wrote: > On 08/08, Johannes Weiner wrote: > > Hi Jaegeuk and Bradley, > > > > On Mon, Aug 07, 2017 at 09:01:50PM -0400, Bradley Bolen wrote: > > > I am getting a very similar error on v4.11 with an arm64 board. > > > > > > I, too, also see pag

Re: kernel panic on null pointer on page->mem_cgroup

2017-08-08 Thread Jaegeuk Kim
On 08/08, Johannes Weiner wrote: > Hi Jaegeuk and Bradley, > > On Mon, Aug 07, 2017 at 09:01:50PM -0400, Bradley Bolen wrote: > > I am getting a very similar error on v4.11 with an arm64 board. > > > > I, too, also see page->mem_cgroup checked to make sure that it is not > > NULL and then several

Re: kernel panic on null pointer on page->mem_cgroup

2017-08-08 Thread Johannes Weiner
Hi Jaegeuk and Bradley, On Mon, Aug 07, 2017 at 09:01:50PM -0400, Bradley Bolen wrote: > I am getting a very similar error on v4.11 with an arm64 board. > > I, too, also see page->mem_cgroup checked to make sure that it is not > NULL and then several instructions later it is NULL. It does appear

kernel panic on null pointer on page->mem_cgroup

2017-08-05 Thread Jaegeuk Kim
Hi Johannes, Can I ask your help about the below panic which is annoying me recently. I'm currently testing xfstests with 4.13-rc2, and have hit the below panic very randomly. [ 3722.366490] BUG: unable to handle kernel NULL pointer dereference at 03b0 [ 3722.378815] IP: test_clear_p