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.ne...@redhat.com
Fixes: 864b75f9d6b01 ("mm/page_alloc: fix memmap_init_zone pageblock alignment")
Signed-off-by: Daniel Vacek <ne...@redhat.com>
Tested-by: Sudeep Holla <sudeep.ho...@arm.com>
Tested-by: Naresh Kamboju <naresh.kamb...@linaro.org>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Mel Gorman <mgor...@techsingularity.net>
Cc: Michal Hocko <mho...@suse.com>
Cc: Paul Burton <paul.bur...@imgtec.com>
Cc: Pavel Tatashin <pasha.tatas...@oracle.com>
Cc: Vlastimil Babka <vba...@suse.cz>
Cc: <sta...@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
