Messages in this thread | | | Subject | Re: [PATCH] mm/page_alloc: fix boot hang in memmap_init_zone | From | Jia He <> | Date | Thu, 15 Mar 2018 22:08:12 +0800 |
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Hi Daniel
On 3/14/2018 6:42 AM, Daniel Vacek Wrote: > On some architectures (reported on arm64) commit 864b75f9d6b01 ("mm/page_alloc: fix memmap_init_zone pageblock alignment") > causes a boot hang. This patch fixes the hang making sure the alignment > never steps back. > > Link: http://lkml.kernel.org/r/0485727b2e82da7efbce5f6ba42524b429d0391a.1520011945.git.neelx@redhat.com > Fixes: 864b75f9d6b01 ("mm/page_alloc: fix memmap_init_zone pageblock alignment") > Signed-off-by: Daniel Vacek <neelx@redhat.com> > Tested-by: Sudeep Holla <sudeep.holla@arm.com> > Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Mel Gorman <mgorman@techsingularity.net> > Cc: Michal Hocko <mhocko@suse.com> > Cc: Paul Burton <paul.burton@imgtec.com> > Cc: Pavel Tatashin <pasha.tatashin@oracle.com> > Cc: Vlastimil Babka <vbabka@suse.cz> > Cc: <stable@vger.kernel.org> > --- > mm/page_alloc.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 3d974cb2a1a1..e033a6895c6f 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -5364,9 +5364,14 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone, > * is not. move_freepages_block() can shift ahead of > * the valid region but still depends on correct page > * metadata. > + * Also make sure we never step back. > */ > - pfn = (memblock_next_valid_pfn(pfn, end_pfn) & > + unsigned long next_pfn; > + > + next_pfn = (memblock_next_valid_pfn(pfn, end_pfn) & > ~(pageblock_nr_pages-1)) - 1; > + if (next_pfn > pfn) > + pfn = next_pfn; It didn't resolve the booting hang issue in my arm64 server. what if memblock_next_valid_pfn(pfn, end_pfn) is 32 and pageblock_nr_pages is 8196? Thus, next_pfn will be (unsigned long)-1 and be larger than pfn. So still there is an infinite loop here.
Cheers, Jia He > #endif > continue; > }
-- Cheers, Jia
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