[CC Joonsoo]
On Tue 09-01-18 16:39:21, Oscar Salvador wrote:
> 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
> RSP: 0000:ffffffff82003ea8 EFLAGS: 00010246
> RAX: 000000000000000f RBX: ffffffffffffffff RCX: ffffffff8205b388
> RDX: 0000000000000001 RSI: 0000000000000096 RDI: 0000000000000202
> RBP: 0000000000000000 R08: 0000000000000000 R09: 00000000000000af
> R10: 0000000000000004 R11: 00000000000000ae R12: ffff88024dfdcec0
> R13: ffffffff82530740 R14: 0000000000000000 R15: 00000000a8831448
> FS: 0000000000000000(0000) GS:ffff88024dc00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: ffff88024dfff000 CR3: 000000000200a001 CR4: 00000000000606b0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> 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
> ---[ end trace 45da7f0cb4aef07b ]---
>
> This warning is showed 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().
I _think_ the patch is correct. The changelog should explain, _why_
removing drain_all_pages is OK. Joonsoo what was the reason to put it
here in the first place? I do not see any real reason. This is an init
code and we shouldn't have any pages on those caches anyway. Moreover I
fail to see why the fact they are on the pcp caches mattered at all.
> Signed-off-by: Oscar Salvador <osalvador@xxxxxxxxxxxxxxxxxx>
> ---
> mm/page_owner.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/mm/page_owner.c b/mm/page_owner.c
> index 8602fb41b293..69f83fc763bb 100644
> --- a/mm/page_owner.c
> +++ b/mm/page_owner.c
> @@ -616,7 +616,6 @@ 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);
> }
> --
> 2.13.5
>
--
Michal Hocko
SUSE Labs
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