| Message ID | CAGM2reaZaJU1WQTyzGiT1zOpjHLv6=hxNfA75JLM4AdbiajrtQ@mail.gmail.com (mailing list archive) |
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I have posted a patch for the above issue: http://lkml.kernel.org/r/20180716151630.770-1-pasha.tatashin@oracle.com On Mon, Jul 16, 2018 at 9:15 AM Pavel Tatashin <pasha.tatashin@oracle.com> wrote: > > I have figured out what is going with x86-32. Since it has FLATMEM > memory layout, the memmap is now allocated after zero_resv_unavail(): > > Now, we have something like this: > > zero_resv_unavail() > free_area_init_node() > #ifdef CONFIG_FLAT_NODE_MEM_MAP > alloc_node_mem_map() > #endif > > At the time when zero_resv_unavail() is called, memmap for > FLAT_NODE_MEM_MAP is not yet allocated. On the other hand, > alloc_node_mem_map() calls memblock_virt_alloc_node_nopanic() which > calls memset(0), so zero_resv_unavail() > is not needed for this layout. > > The fix is: > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 5d800d61ddb7..9ec34218713b 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -6847,7 +6847,9 @@ void __init free_area_init_nodes(unsigned long > *max_zone_pfn) > /* Initialise every node */ > mminit_verify_pageflags_layout(); > setup_nr_node_ids(); > +#ifndef CONFIG_FLAT_NODE_MEM_MAP > zero_resv_unavail(); > +#endif > for_each_online_node(nid) { > pg_data_t *pgdat = NODE_DATA(nid); > free_area_init_node(nid, NULL, > > This is just a temporary fix, I will do a proper fix later, when I > will get rid of zero_resv_unavail(), but that will require more > thinking, on how to ensure that no section in memmap is skipped while > we go through memmap_init_zone(). > > Should I submit an updated patch for "mm: zero unavailable pages > before memmap init", or just this incremental fix? > > Thank you, > Pavel > > On Mon, Jul 16, 2018 at 7:56 AM Pavel Tatashin > <pasha.tatashin@oracle.com> wrote: > > > > I have reproduced the problem on mainline. Use x86_32 defcontig + > > qemu, and problem is reproduced immediately. I will send an update > > once I figure out what is going on. > > > > Pavel > > On Mon, Jul 16, 2018 at 7:02 AM Greg Kroah-Hartman > > <gregkh@linuxfoundation.org> wrote: > > > > > > 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 > > >
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 5d800d61ddb7..9ec34218713b 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6847,7 +6847,9 @@ void __init free_area_init_nodes(unsigned long *max_zone_pfn) /* Initialise every node */ mminit_verify_pageflags_layout(); setup_nr_node_ids(); +#ifndef CONFIG_FLAT_NODE_MEM_MAP zero_resv_unavail(); +#endif for_each_online_node(nid) { pg_data_t *pgdat = NODE_DATA(nid);
I have figured out what is going with x86-32. Since it has FLATMEM memory layout, the memmap is now allocated after zero_resv_unavail(): Now, we have something like this: zero_resv_unavail() free_area_init_node() #ifdef CONFIG_FLAT_NODE_MEM_MAP alloc_node_mem_map() #endif At the time when zero_resv_unavail() is called, memmap for FLAT_NODE_MEM_MAP is not yet allocated. On the other hand, alloc_node_mem_map() calls memblock_virt_alloc_node_nopanic() which calls memset(0), so zero_resv_unavail() is not needed for this layout. The fix is: free_area_init_node(nid, NULL, This is just a temporary fix, I will do a proper fix later, when I will get rid of zero_resv_unavail(), but that will require more thinking, on how to ensure that no section in memmap is skipped while we go through memmap_init_zone(). Should I submit an updated patch for "mm: zero unavailable pages before memmap init", or just this incremental fix? Thank you, Pavel On Mon, Jul 16, 2018 at 7:56 AM Pavel Tatashin <pasha.tatashin@oracle.com> wrote: > > I have reproduced the problem on mainline. Use x86_32 defcontig + > qemu, and problem is reproduced immediately. I will send an update > once I figure out what is going on. > > Pavel > On Mon, Jul 16, 2018 at 7:02 AM Greg Kroah-Hartman > <gregkh@linuxfoundation.org> wrote: > > > > 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 > >