On Fri 2018-11-02 22:31:56, Tetsuo Handa wrote:
> syzbot is sometimes getting mixed output like below due to concurrent
> printk(). Mitigate such output by using line-buffered printk() API.
>
> Node 0 DMA: 1*4kB (U) 0*8kB 0*16kB 1*32kB
> syz-executor0: page allocation failure: order:0, mode:0x484020(GFP_ATOMIC|__GFP_COMP), nodemask=(null)
> (U)
> syz-executor0 cpuset=
> 2*64kB
> syz0
> (U)
> mems_allowed=0
> 1*128kB
> CPU: 0 PID: 7592 Comm: syz-executor0 Not tainted 4.19.0-rc6+ #118
> (U)
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> 1*256kB (U)
> Call Trace:
> 0*512kB
> <IRQ>
> 1*1024kB
> __dump_stack lib/dump_stack.c:77 [inline]
> dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113
> (U)
> 1*2048kB
> warn_alloc.cold.119+0xb7/0x1bd mm/page_alloc.c:3426
> (M)
>
> Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> ---
> mm/page_alloc.c | 32 +++++++++++++++++---------------
> 1 file changed, 17 insertions(+), 15 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index a919ba5..4411d5a 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -4694,10 +4694,10 @@ unsigned long nr_free_pagecache_pages(void)
> return nr_free_zone_pages(gfp_zone(GFP_HIGHUSER_MOVABLE));
> }
>
> -static inline void show_node(struct zone *zone)
> +static inline void show_node(struct zone *zone, struct printk_buffer *buf)
> {
> if (IS_ENABLED(CONFIG_NUMA))
> - printk("Node %d ", zone_to_nid(zone));
> + printk_buffered(buf, "Node %d ", zone_to_nid(zone));
The conversion looks fine to me. I just think about renaming
printk_buffered to bprintk().
Best Regards,
Petr
