On Fri, Jul 15, 2016 at 02:09:25PM +0100, Mel Gorman wrote: > Minchan Kim reported setting the following warning on a 32-bit system > although it can affect 64-bit systems. > > WARNING: CPU: 4 PID: 1322 at mm/memcontrol.c:998 mem_cgroup_update_lru_size+0x103/0x110 > mem_cgroup_update_lru_size(f44b4000, 1, -7): zid 1 lru_size 1 but empty > Modules linked in: > CPU: 4 PID: 1322 Comm: cp Not tainted 4.7.0-rc4-mm1+ #143 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 > 00000086 00000086 c2bc5a10 db3e4a97 c2bc5a54 db9d4025 c2bc5a40 db07b82a > db9d0594 c2bc5a70 0000052a db9d4025 000003e6 db208463 000003e6 00000001 > f44b4000 00000001 c2bc5a5c db07b88b 00000009 00000000 c2bc5a54 db9d0594 > Call Trace: > [<db3e4a97>] dump_stack+0x76/0xaf > [<db07b82a>] __warn+0xea/0x110 > [<db208463>] ? mem_cgroup_update_lru_size+0x103/0x110 > [<db07b88b>] warn_slowpath_fmt+0x3b/0x40 > [<db208463>] mem_cgroup_update_lru_size+0x103/0x110 > [<db1b52a2>] isolate_lru_pages.isra.61+0x2e2/0x360 > [<db1b6ffc>] shrink_active_list+0xac/0x2a0 > [<db3f136e>] ? __delay+0xe/0x10 > [<db1b772c>] shrink_node_memcg+0x53c/0x7a0 > [<db1b7a3b>] shrink_node+0xab/0x2a0 > [<db1b7cf6>] do_try_to_free_pages+0xc6/0x390 > [<db1b8205>] try_to_free_pages+0x245/0x590 > > LRU list contents and counts are updated separately. Counts are updated > before pages are added to the LRU and updated after pages are removed. > The warning above is from a check in mem_cgroup_update_lru_size that > ensures that list sizes of zero are empty. > > The problem is that node-lru needs to account for highmem pages if > CONFIG_HIGHMEM is set. One impact of the implementation is that the > sizes are updated in multiple passes when pages from multiple zones were > isolated. This happens whether HIGHMEM is set or not. When multiple zones > are isolated, it's possible for a debugging check in memcg to be tripped. > > This patch forces all the zone counts to be updated before the memcg > function is called. > > Reported-and-tested-by: Minchan Kim <minchan@xxxxxxxxxx> > Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Acked-by: Minchan Kim <minchan@xxxxxxxxxx> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>