Message-ID: <20180716105451.GA20734@sirena.org.uk>
Date:   Mon, 16 Jul 2018 11:54:51 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Guillaume Tucker <guillaume.tucker@...labora.com>
Cc:     Pavel Tatashin <pasha.tatashin@...cle.com>, linux-mm@...ck.org,
        kernel@...labora.com, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org, kernel-build-reports@...ts.linaro.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: mainline/master boot: 177 boots: 2 failed, 174 passed with 1
 conflict (v4.18-rc4-160-gf353078f028f)

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.

> 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@...cle.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@...cle.com>
>     Signed-off-by: Linus Torvalds <torvalds@...ux-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)
> -------------------------------------------------------------------------------
> 
> 
> Git bisection log:
> 
> -------------------------------------------------------------------------------
> git bisect start
> # good: [2db39a2f491a48ec740e0214a7dd584eefc2137d] Merge branch 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux
> git bisect good 2db39a2f491a48ec740e0214a7dd584eefc2137d
> # bad: [f353078f028fbfe9acd4b747b4a19c69ef6846cd] Merge branch 'akpm' (patches from Andrew)
> git bisect bad f353078f028fbfe9acd4b747b4a19c69ef6846cd
> # good: [fa8cbda88db12e632a8987c94b66f5caf25bcec4] x86/purgatory: add missing FORCE to Makefile target
> git bisect good fa8cbda88db12e632a8987c94b66f5caf25bcec4
> # good: [bb177a732c4369bb58a1fe1df8f552b6f0f7db5f] mm: do not bug_on on incorrect length in __mm_populate()
> git bisect good bb177a732c4369bb58a1fe1df8f552b6f0f7db5f
> # good: [fe10e398e860955bac4d28ec031b701d358465e4] reiserfs: fix buffer overflow with long warning messages
> git bisect good fe10e398e860955bac4d28ec031b701d358465e4
> # bad: [e181ae0c5db9544de9c53239eb22bc012ce75033] mm: zero unavailable pages before memmap init
> git bisect bad e181ae0c5db9544de9c53239eb22bc012ce75033
> # first bad commit: [e181ae0c5db9544de9c53239eb22bc012ce75033] mm: zero unavailable pages before memmap init
> -------------------------------------------------------------------------------
> 
> _______________________________________________
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> Kernel-build-reports@...ts.linaro.org
> https://lists.linaro.org/mailman/listinfo/kernel-build-reports

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