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Date:   Mon, 16 Jul 2018 13:02:08 +0200
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Mark Brown <broonie@kernel.org>
Cc:     Guillaume Tucker <guillaume.tucker@collabora.com>,
        Pavel Tatashin <pasha.tatashin@oracle.com>, linux-mm@kvack.org,
        kernel@collabora.com, linux-kernel@vger.kernel.org,
        stable@vger.kernel.org, kernel-build-reports@lists.linaro.org
Subject: Re: mainline/master boot: 177 boots: 2 failed, 174 passed with 1
 conflict (v4.18-rc4-160-gf353078f028f)
Message-ID: <20180716110208.GA25227@kroah.com>
References: <5b4a9633.1c69fb81.17984.f7b3@mx.google.com>
 <0ab16066-5498-374b-5391-3dd7979044aa@collabora.com>
 <20180716105451.GA20734@sirena.org.uk>
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On Mon, Jul 16, 2018 at 11:54:51AM +0100, Mark Brown wrote:
> On Mon, Jul 16, 2018 at 11:40:06AM +0100, Guillaume Tucker wrote:
> > On 15/07/18 01:32, kernelci.org bot wrote:
> > > mainline/master boot: 177 boots: 2 failed, 174 passed with 1 conflict (v4.18-rc4-160-gf353078f028f)
> > > 
> > > Full Boot Summary: https://kernelci.org/boot/all/job/mainline/branch/master/kernel/v4.18-rc4-160-gf353078f028f/
> > > Full Build Summary: https://kernelci.org/build/mainline/branch/master/kernel/v4.18-rc4-160-gf353078f028f/
> > > 
> > > Tree: mainline
> > > Branch: master
> > > Git Describe: v4.18-rc4-160-gf353078f028f
> > > Git Commit: f353078f028fbfe9acd4b747b4a19c69ef6846cd
> > > Git URL: http://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> > > Tested: 67 unique boards, 25 SoC families, 21 builds out of 199
> > > 
> > > Boot Regressions Detected:
> > [...]
> > > x86:
> > > 
> > >      i386_defconfig:
> > >          x86-celeron:
> > >              lab-mhart: new failure (last pass: v4.18-rc4-147-g2db39a2f491a)
> > >          x86-pentium4:
> > >              lab-mhart: new failure (last pass: v4.18-rc4-147-g2db39a2f491a)
> > 
> > Please see below an automated bisection report for this
> > regression.  Several bisections were run on other x86 platforms
> > with i386_defconfig on a few revisions up to v4.18-rc5, they all
> > reached the same "bad" commit.
> > 
> > 
> > Unfortunately there isn't much to learn from the kernelci.org
> > boot logs as the kernel seems to crash very early on:
> > 
> >     https://kernelci.org/boot/all/job/mainline/branch/master/kernel/v4.18-rc5/
> >     https://storage.kernelci.org/mainline/master/v4.18-rc4-160-gf353078f028f/x86/i386_defconfig/lab-mhart/lava-x86-celeron.html
> > 
> > 
> > It looks like stable-rc/linux-4.17.y is also broken with
> > i386_defconfig, which tends to confirm the "bad" commit found by
> > the automated bisection which was applied there as well:
> > 
> >     https://kernelci.org/boot/all/job/stable-rc/branch/linux-4.17.y/kernel/v4.17.6-68-gbc0bd9e05fa1/
> 
> Adding Greg directly to the CCs due to the stable impact, not deleting
> context for his benefit.

Hey, I read all stable emails, who else would?  :)

> > The automated bisection on kernelci.org is still quite new, so
> > please take the results with a pinch of salt as the "bad" commit
> > found may not be the actual root cause of the boot failure.
> > 
> > Hope this helps!
> > 
> > Best wishes,
> > Guillaume
> > 
> > 
> > --------------------------------------8<--------------------------------------
> > 
> > 
> > 
> > Bisection result for mainline/master (v4.18-rc4-160-gf353078f028f) on x86-celeron
> > 
> >   Good:       2db39a2f491a Merge branch 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux
> >   Bad:        f353078f028f Merge branch 'akpm' (patches from Andrew)
> >   Found:      e181ae0c5db9 mm: zero unavailable pages before memmap init
> > 
> > Checks:
> >   revert:     PASS
> >   verify:     PASS
> > 
> > Parameters:
> >   Tree:       mainline
> >   URL:        http://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> >   Branch:     master
> >   Target:     x86-celeron
> >   Lab:        lab-mhart
> >   Config:     i386_defconfig
> >   Plan:       boot
> > 
> > Breaking commit found:
> > 
> > -------------------------------------------------------------------------------
> > commit e181ae0c5db9544de9c53239eb22bc012ce75033
> > Author: Pavel Tatashin <pasha.tatashin@oracle.com>
> > Date:   Sat Jul 14 09:15:07 2018 -0400
> > 
> >     mm: zero unavailable pages before memmap init
> >     We must zero struct pages for memory that is not backed by physical
> >     memory, or kernel does not have access to.
> >     Recently, there was a change which zeroed all memmap for all holes in
> >     e820.  Unfortunately, it introduced a bug that is discussed here:
> >       https://www.spinics.net/lists/linux-mm/msg156764.html
> >     Linus, also saw this bug on his machine, and confirmed that reverting
> >     commit 124049decbb1 ("x86/e820: put !E820_TYPE_RAM regions into
> >     memblock.reserved") fixes the issue.
> >     The problem is that we incorrectly zero some struct pages after they
> >     were setup.
> >     The fix is to zero unavailable struct pages prior to initializing of
> >     struct pages.
> >     A more detailed fix should come later that would avoid double zeroing
> >     cases: one in __init_single_page(), the other one in
> >     zero_resv_unavail().
> >     Fixes: 124049decbb1 ("x86/e820: put !E820_TYPE_RAM regions into memblock.reserved")
> >     Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
> >     Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
> > 
> > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > index 1521100f1e63..5d800d61ddb7 100644
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -6847,6 +6847,7 @@ void __init free_area_init_nodes(unsigned long *max_zone_pfn)
> >  	/* Initialise every node */
> >  	mminit_verify_pageflags_layout();
> >  	setup_nr_node_ids();
> > +	zero_resv_unavail();
> >  	for_each_online_node(nid) {
> >  		pg_data_t *pgdat = NODE_DATA(nid);
> >  		free_area_init_node(nid, NULL,
> > @@ -6857,7 +6858,6 @@ void __init free_area_init_nodes(unsigned long *max_zone_pfn)
> >  			node_set_state(nid, N_MEMORY);
> >  		check_for_memory(pgdat, nid);
> >  	}
> > -	zero_resv_unavail();
> >  }
> >  static int __init cmdline_parse_core(char *p, unsigned long *core,
> > @@ -7033,9 +7033,9 @@ void __init set_dma_reserve(unsigned long new_dma_reserve)
> >  void __init free_area_init(unsigned long *zones_size)
> >  {
> > +	zero_resv_unavail();
> >  	free_area_init_node(0, zones_size,
> >  			__pa(PAGE_OFFSET) >> PAGE_SHIFT, NULL);
> > -	zero_resv_unavail();
> >  }
> >  static int page_alloc_cpu_dead(unsigned int cpu)
> > -------------------------------------------------------------------------------

So this patch breaks i386, ick.  I'll wait for the fix to hit Linus's
tree as that's a bit more important to have the large majority of the
x86-64 boxes fixed with this patch for now.

thanks,

greg k-h