From: Oscar Salvador osalvador@techadventures.net

commit u6bec6ad77fac3d29aed0d8e0b7526daedc964970 upstream.

When setting page_owner = on, the following warning can be seen in the boot log:

WARNING: CPU: 0 PID: 0 at mm/page_alloc.c:2537 drain_all_pages+0x171/0x1a0 Modules linked in: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.15.0-rc7-next-20180109-1-default+ #7 Hardware name: Dell Inc. Latitude E7470/0T6HHJ, BIOS 1.11.3 11/09/2016 RIP: 0010:drain_all_pages+0x171/0x1a0 Call Trace: init_page_owner+0x4e/0x260 start_kernel+0x3e6/0x4a6 ? set_init_arg+0x55/0x55 secondary_startup_64+0xa5/0xb0 Code: c5 ed ff 89 df 48 c7 c6 20 3b 71 82 e8 f9 4b 52 00 3b 05 d7 0b f8 00 89 c3 72 d5 5b 5d 41 5

This warning is shown because we are calling drain_all_pages() in init_early_allocated_pages(), but mm_percpu_wq is not up yet, it is being set up later on in kernel_init_freeable() -> init_mm_internals().

Link: http://lkml.kernel.org/r/20180109153921.GA13070@techadventures.net Signed-off-by: Oscar Salvador osalvador@techadventures.net Acked-by: Joonsoo Kim iamjoonsoo.kim@lge.com Cc: Vlastimil Babka vbabka@suse.cz Cc: Michal Hocko mhocko@suse.com Cc: Ayush Mittal ayush.m@samsung.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Nick Desaulniers ndesaulniers@google.com --- Fixes an easliy reproduced WARN_ON_ONCE observed with CONFIG_PAGE_OWNER=y and page_owner=on boot param. Looks like this landed in v4.15-rc9 but hasn't been backported yet. Thanks to Miles Chen miles.chen@mediatek.com for the report.

mm/page_owner.c | 1 - 1 file changed, 1 deletion(-)

diff --git a/mm/page_owner.c b/mm/page_owner.c index 6ac05a6ff2d1..4753b317ef7b 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -617,7 +617,6 @@ static void init_early_allocated_pages(void) { pg_data_t *pgdat;

- drain_all_pages(NULL); for_each_online_pgdat(pgdat) init_zones_in_node(pgdat); }