• Yue Hu's avatar
    mm/cma.c: fix the bitmap status to show failed allocation reason · 20fbb34e
    Yue Hu authored
    [ Upstream commit 2b59e01a3aa665f751d1410b99fae9336bd424e1 ]
    Currently one bit in cma bitmap represents number of pages rather than
    one page, cma->count means cma size in pages. So to find available pages
    via find_next_zero_bit()/find_next_bit() we should use cma size not in
    pages but in bits although current free pages number is correct due to
    zero value of order_per_bit. Once order_per_bit is changed the bitmap
    status will be incorrect.
    The size input in cma_debug_show_areas() is not correct.  It will
    affect the available pages at some position to debug the failure issue.
    This is an example with order_per_bit = 1
    Before this change:
    [    4.120060] cma: number of available pages: 1@93+4@108+7@121+7@137+7@153+7@169+7@185+7@201+3@213+3@221+3@229+3@237+3@245+3@253+3@261+3@269+3@277+3@285+3@293+3@301+3@309+3@317+3@325+19@333+15@369+512@512=> 638 free of 1024 total pages
    After this change:
    [    4.143234] cma: number of available pages: 2@93+8@108+14@121+14@137+14@153+14@169+14@185+14@201+6@213+6@221+6@229+6@237+6@245+6@253+6@261+6@269+6@277+6@285+6@293+6@301+6@309+6@317+6@325+38@333+30@369=> 252 free of 1024 total pages
    Obviously the bitmap status before is incorrect.
    Link: http://lkml.kernel.org/r/20190320060829.9144-1-zbestahu@gmail.comSigned-off-by: default avatarYue Hu <huyue2@yulong.com>
    Reviewed-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
    Cc: Ingo Molnar <mingo@kernel.org>
    Cc: Vlastimil Babka <vbabka@suse.cz>
    Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
    Cc: Randy Dunlap <rdunlap@infradead.org>
    Cc: Laura Abbott <labbott@redhat.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: default avatarSasha Levin <sashal@kernel.org>