• Vlastimil Babka's avatar
    mm, page_owner: print migratetype of page and pageblock, symbolic flags · 60f30350
    Vlastimil Babka authored
    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 520 type Movable Block 1 type Movable Flags 0xfffff8001006c(referenced|uptodate|lru|active|mappedtodisk)
       [<ffffffff811682c4>] __alloc_pages_nodemask+0x134/0x230
       [<ffffffff811b4058>] alloc_pages_current+0x88/0x120
       [<ffffffff8115e386>] __page_cache_alloc+0xe6/0x120
       [<ffffffff8116ba6c>] __do_page_cache_readahead+0xdc/0x240
       [<ffffffff8116bd05>] ondemand_readahead+0x135/0x260
       [<ffffffff8116bfb1>] page_cache_sync_readahead+0x31/0x50
       [<ffffffff81160523>] generic_file_read_iter+0x453/0x760
       [<ffffffff811e0d57>] __vfs_read+0xa7/0xd0
    Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
    Acked-by: default avatarMichal Hocko <mhocko@suse.com>
    Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
    Cc: Minchan Kim <minchan@kernel.org>
    Cc: Sasha Levin <sasha.levin@oracle.com>
    Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
    Cc: Mel Gorman <mgorman@suse.de>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
mmzone.h 37.1 KB