On Fri 18-12-15 10:03:21, Vlastimil Babka wrote: > The information in /sys/kernel/debug/page_owner includes the migratetype of > the pageblock the page belongs to. This is also checked against the page's > migratetype (as declared by gfp_flags during its allocation), and the page is > reported as Fallback if its migratetype differs from the pageblock's one. > t > This is somewhat misleading because in fact fallback allocation is not the only > reason why these two can differ. It also doesn't direcly provide the page's > migratetype, although it's possible to derive that from the gfp_flags. > > It's arguably better to print both page and pageblock's migratetype and leave > the interpretation to the consumer than to suggest fallback allocation as the > only possible reason. While at it, we can print the migratetypes as string > the same way as /proc/pagetypeinfo does, as some of the numeric values depend > on kernel configuration. For that, this patch moves the migratetype_names > array from #ifdef CONFIG_PROC_FS part of mm/vmstat.c to mm/page_alloc.c and > exports it. > > With the new format strings for flags, we can now also provide symbolic page > and gfp flags in the /sys/kernel/debug/page_owner file. This replaces the > positional printing of page flags as single letters, which might have looked > nicer, but was limited to a subset of flags, and required the user to remember > the letters. > > Example page_owner entry after the patch: > > Page allocated via order 0, mask 0x24213ca(GFP_HIGHUSER_MOVABLE|GFP_COLD|GFP_NOWARN|GFP_NORETRY) > PFN 674308 type Movable Block 1317 type Movable Flags 0x1fffff80010068(uptodate|lru|active|mappedtodisk) > [<ffffffff81164e9a>] __alloc_pages_nodemask+0x15a/0xa30 > [<ffffffff811ab938>] alloc_pages_current+0x88/0x120 > [<ffffffff8115bc46>] __page_cache_alloc+0xe6/0x120 > [<ffffffff81168b9b>] __do_page_cache_readahead+0xdb/0x200 > [<ffffffff81168df5>] ondemand_readahead+0x135/0x260 > [<ffffffff81168f8c>] page_cache_async_readahead+0x6c/0x70 > [<ffffffff8115d5f8>] generic_file_read_iter+0x378/0x590 > [<ffffffff811d12a7>] __vfs_read+0xa7/0xd0 > > Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> > Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> > Cc: Minchan Kim <minchan@xxxxxxxxxx> > Cc: Sasha Levin <sasha.levin@xxxxxxxxxx> > Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> > Cc: Mel Gorman <mgorman@xxxxxxx> > Cc: Michal Hocko <mhocko@xxxxxxx> Looks good to me Acked-by: Michal Hocko <mhocko@xxxxxxxx> > --- > include/linux/mmzone.h | 3 +++ > mm/page_alloc.c | 13 +++++++++++++ > mm/page_owner.c | 24 +++++++----------------- > mm/vmstat.c | 13 ------------- > 4 files changed, 23 insertions(+), 30 deletions(-) > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index 33bb1b19273e..68cc063bf0b7 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -63,6 +63,9 @@ enum { > MIGRATE_TYPES > }; > > +/* In mm/page_alloc.c; keep in sync also with show_migration_types() there */ > +extern char * const migratetype_names[MIGRATE_TYPES]; > + > #ifdef CONFIG_CMA > # define is_migrate_cma(migratetype) unlikely((migratetype) == MIGRATE_CMA) > #else > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 08e514721a57..67538b58e478 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -222,6 +222,19 @@ static char * const zone_names[MAX_NR_ZONES] = { > #endif > }; > > +char * const migratetype_names[MIGRATE_TYPES] = { > + "Unmovable", > + "Movable", > + "Reclaimable", > + "HighAtomic", > +#ifdef CONFIG_CMA > + "CMA", > +#endif > +#ifdef CONFIG_MEMORY_ISOLATION > + "Isolate", > +#endif > +}; > + > compound_page_dtor * const compound_page_dtors[] = { > NULL, > free_compound_page, > diff --git a/mm/page_owner.c b/mm/page_owner.c > index 983c3a10fa07..5392195fca61 100644 > --- a/mm/page_owner.c > +++ b/mm/page_owner.c > @@ -100,8 +100,9 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn, > return -ENOMEM; > > ret = snprintf(kbuf, count, > - "Page allocated via order %u, mask 0x%x\n", > - page_ext->order, page_ext->gfp_mask); > + "Page allocated via order %u, mask %#x(%pgg)\n", > + page_ext->order, page_ext->gfp_mask, > + &page_ext->gfp_mask); > > if (ret >= count) > goto err; > @@ -110,23 +111,12 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn, > pageblock_mt = get_pfnblock_migratetype(page, pfn); > page_mt = gfpflags_to_migratetype(page_ext->gfp_mask); > ret += snprintf(kbuf + ret, count - ret, > - "PFN %lu Block %lu type %d %s Flags %s%s%s%s%s%s%s%s%s%s%s%s\n", > + "PFN %lu type %s Block %lu type %s Flags %#lx(%pgp)\n", > pfn, > + migratetype_names[page_mt], > pfn >> pageblock_order, > - pageblock_mt, > - pageblock_mt != page_mt ? "Fallback" : " ", > - PageLocked(page) ? "K" : " ", > - PageError(page) ? "E" : " ", > - PageReferenced(page) ? "R" : " ", > - PageUptodate(page) ? "U" : " ", > - PageDirty(page) ? "D" : " ", > - PageLRU(page) ? "L" : " ", > - PageActive(page) ? "A" : " ", > - PageSlab(page) ? "S" : " ", > - PageWriteback(page) ? "W" : " ", > - PageCompound(page) ? "C" : " ", > - PageSwapCache(page) ? "B" : " ", > - PageMappedToDisk(page) ? "M" : " "); > + migratetype_names[pageblock_mt], > + page->flags, &page->flags); > > if (ret >= count) > goto err; > diff --git a/mm/vmstat.c b/mm/vmstat.c > index dfe7315f2db6..475d154411f0 100644 > --- a/mm/vmstat.c > +++ b/mm/vmstat.c > @@ -924,19 +924,6 @@ static void walk_zones_in_node(struct seq_file *m, pg_data_t *pgdat, > #endif > > #ifdef CONFIG_PROC_FS > -static char * const migratetype_names[MIGRATE_TYPES] = { > - "Unmovable", > - "Movable", > - "Reclaimable", > - "HighAtomic", > -#ifdef CONFIG_CMA > - "CMA", > -#endif > -#ifdef CONFIG_MEMORY_ISOLATION > - "Isolate", > -#endif > -}; > - > static void frag_show_print(struct seq_file *m, pg_data_t *pgdat, > struct zone *zone) > { > -- > 2.6.3 -- Michal Hocko SUSE Labs -- 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>