On 2019-10-11 23:32, Qian Cai wrote:
# /opt/ltp/runtest/bin/move_pages12
move_pages12.c:263: INFO: Free RAM 258988928 kB
move_pages12.c:281: INFO: Increasing 2048kB hugepages pool on node 0 to
4
move_pages12.c:291: INFO: Increasing 2048kB hugepages pool on node 8 to
4
move_pages12.c:207: INFO: Allocating and freeing 4 hugepages on node 0
move_pages12.c:207: INFO: Allocating and freeing 4 hugepages on node 8
move_pages12.c:197: PASS: Bug not reproduced
move_pages12.c:197: PASS: Bug not reproduced
for mem in $(ls -d /sys/devices/system/memory/memory*); do
echo offline > $mem/state
echo online > $mem/state
done
That LTP move_pages12 test will first madvise(MADV_SOFT_OFFLINE) for a
range.
Then, one of "echo offline" will trigger an infinite loop in
__offline_pages()
here,
I did not deeply check whether this issue is really related
soft-offline.
As is, soft-offline has a few issues that can lead to tricky problems.
Actually, lately I have received quite a few reports from customers
where testing soft-offline
resulted in applications crashing all around.
I am working on a re-implementation to fix those issues [1].
I yet have to fix a bug I found yesterday though, but it should be quite
trivial to fix it up, so I should be able to send a new re-spin next
week.
[1] https://lore.kernel.org/patchwork/cover/1126173/
Thanks
/* check again */
ret = walk_system_ram_range(start_pfn, end_pfn - start_pfn,
NULL, check_pages_isolated_cb);
} while (ret);
because check_pages_isolated_cb() always return -EBUSY from
test_pages_isolated(),
pfn = __test_page_isolated_in_pageblock(start_pfn, end_pfn,
skip_hwpoisoned_pages);
...
return pfn < end_pfn ? -EBUSY : 0;
The root cause is in __test_page_isolated_in_pageblock() where "pfn" is
always
less than "end_pfn" because the associated page is not a PageBuddy.
while (pfn < end_pfn) {
...
else
break;
return pfn;
Adding a dump_page() for that pfn shows,
[ 101.665160][ T8885] pfn = 77501, end_pfn = 78000
[ 101.665245][ T8885] page:c00c000001dd4040 refcount:0 mapcount:0
mapping:0000000000000000 index:0x0
[ 101.665329][ T8885] flags: 0x3fffc000000000()
[ 101.665391][ T8885] raw: 003fffc000000000 0000000000000000
ffffffff01dd0500
0000000000000000
[ 101.665498][ T8885] raw: 0000000000000000 0000000000000000
00000000ffffffff
0000000000000000
[ 101.665588][ T8885] page dumped because: soft_offline
[ 101.665639][ T8885] page_owner tracks the page as freed
[ 101.665697][ T8885] page last allocated via order 5, migratetype
Movable,
gfp_mask
0x346cca(GFP_HIGHUSER_MOVABLE|__GFP_NOWARN|__GFP_RETRY_MAYFAIL|__GFP_COMP|__GFP_
THISNODE)
[ 101.665924][ T8885] prep_new_page+0x3c0/0x440
[ 101.665962][ T8885] get_page_from_freelist+0x2568/0x2bb0
[ 101.666059][ T8885] __alloc_pages_nodemask+0x1b4/0x670
[ 101.666115][ T8885] alloc_fresh_huge_page+0x244/0x6e0
[ 101.666183][ T8885] alloc_migrate_huge_page+0x30/0x70
[ 101.666254][ T8885] alloc_new_node_page+0xc4/0x380
[ 101.666325][ T8885] migrate_pages+0x3b4/0x19e0
[ 101.666375][ T8885] do_move_pages_to_node.isra.29.part.30+0x44/0xa0
[ 101.666464][ T8885] kernel_move_pages+0x498/0xfc0
[ 101.666520][ T8885] sys_move_pages+0x28/0x40
[ 101.666643][ T8885] system_call+0x5c/0x68
[ 101.666665][ T8885] page last free stack trace:
[ 101.666704][ T8885] __free_pages_ok+0xa4c/0xd40
[ 101.666773][ T8885] update_and_free_page+0x2dc/0x5b0
[ 101.666821][ T8885] free_huge_page+0x2dc/0x740
[ 101.666875][ T8885] __put_compound_page+0x64/0xc0
[ 101.666926][ T8885] putback_active_hugepage+0x228/0x390
[ 101.666990][ T8885] migrate_pages+0xa78/0x19e0
[ 101.667048][ T8885] soft_offline_page+0x314/0x1050
[ 101.667117][ T8885] sys_madvise+0x1068/0x1080
[ 101.667185][ T8885] system_call+0x5c/0x68
