Re: [RFC PATCH] mm: reduce noise in show_mem for lowmem allocations

[Vlastimil Babka <vbabka@suse.cz>]

On 8/25/22 11:59, Michal Hocko wrote:
> On Thu 25-08-22 11:52:09, Vlastimil Babka wrote:
>> On 8/23/22 11:22, Michal Hocko wrote:
>> > All but node0 are really completely irrelevant for this allocation
>> > because they do not have ZONE_DMA yet it swamps the log and makes it
>> > harder to visually inspect.
>> > 
>> > Address this by providing gfp_maks parameter to show_mem and filter the
>> > output to only those zones/nodes which are relevant for the allocation.
>> > That means nodes which have at least one managed zone which is usable
>> > for the allocation (zone_idx(zone) <= gfp_zone(gfp_mask)).
>> > The resulting output for the same failure would become:
>> 
>> Looks good to me.
>> 
>> > [...]
>> > [   14.017605][    T1] Mem-Info:
>> 
>> Maybe print the gfp_mask (or just max zone) here again, to make it more
>> obvious in case somebody sents a report without the top header?
> 
> I have tried to not alter the output but rather filter it out. The gfp
> mask is the first line of the allocation failure and from my past
> experience it is usually included in reports.

OK

>> > [   14.017956][    T1] active_anon:0 inactive_anon:0 isolated_anon:0
>> > [   14.017956][    T1]  active_file:0 inactive_file:0 isolated_file:0
>> > [   14.017956][    T1]  unevictable:0 dirty:0 writeback:0
>> > [   14.017956][    T1]  slab_reclaimable:876 slab_unreclaimable:30300
>> > [   14.017956][    T1]  mapped:0 shmem:0 pagetables:12 bounce:0
>> > [   14.017956][    T1]  free:3170151735 free_pcp:6868 free_cma:0
>> > [   14.017962][    T1] Node 0 active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:0kB dirty:0kB writeback:0kB shmem:0kB shmem_thp: 0kB shmem_pmdmapped: 0kB anon_thp: 0kB writeback_tmp:0kB kernel_stack:7200kB pagetables:4kB all_unreclaimable? no
>> > [   14.018026][    T1] Node 0 DMA free:160kB boost:0kB min:0kB low:0kB high:0kB reserved_highatomic:0KB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:15996kB managed:15360kB mlocked:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
>> > [   14.018035][    T1] lowmem_reserve[]: 0 0 0 0 0
>> > [   14.018339][    T1] Node 0 DMA: 0*4kB 0*8kB 0*16kB 1*32kB (U) 0*64kB 1*128kB (U) 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 160kB
>> > [   14.018480][    T1] 0 total pagecache pages
>> > [   14.018483][    T1] 0 pages in swap cache
>> > [   14.018484][    T1] Swap cache stats: add 0, delete 0, find 0/0
>> > [   14.018486][    T1] Free swap  = 0kB
>> > [   14.018487][    T1] Total swap = 0kB
>> > [   14.018488][    T1] 3221164600 pages RAM
>> > [   14.018489][    T1] 0 pages HighMem/MovableOnly
>> > [   14.018490][    T1] 50531051 pages reserved
>> > [   14.018491][    T1] 0 pages cma reserved
>> > [   14.018492][    T1] 0 pages hwpoisoned
>> > 
>> > Signed-off-by: Michal Hocko <mhocko@suse.com>

Acked-by: Vlastimil Babka <vbabka@suse.cz>