• Huang Ying's avatar
    mm, swap: fix THP swap out · 1a5f439c
    Huang Ying authored
    0-Day test system reported some OOM regressions for several THP
    (Transparent Huge Page) swap test cases.  These regressions are bisected
    to 68614289 ("block: always define BIO_MAX_PAGES as 256").  In the
    commit, BIO_MAX_PAGES is set to 256 even when THP swap is enabled.  So the
    bio_alloc(gfp_flags, 512) in get_swap_bio() may fail when swapping out
    THP.  That causes the OOM.
    
    As in the patch description of 68614289 ("block: always define
    BIO_MAX_PAGES as 256"), THP swap should use multi-page bvec to write THP
    to swap space.  So the issue is fixed via doing that in get_swap_bio().
    
    BTW: I remember I have checked the THP swap code when 68614289
    ("block: always define BIO_MAX_PAGES as 256") was merged, and thought the
    THP swap code needn't to be changed.  But apparently, I was wrong.  I
    should have done this at that time.
    
    Link: http://lkml.kernel.org/r/20190624075515.31040-1-ying.huang@intel.com
    Fixes: 68614289 ("block: always define BIO_MAX_PAGES as 256")
    Signed-off-by: default avatar"Huang, Ying" <ying.huang@intel.com>
    Reviewed-by: default avatarMing Lei <ming.lei@redhat.com>
    Cc: Michal Hocko <mhocko@kernel.org>
    Cc: Johannes Weiner <hannes@cmpxchg.org>
    Cc: Hugh Dickins <hughd@google.com>
    Cc: Minchan Kim <minchan@kernel.org>
    Cc: Rik van Riel <riel@redhat.com>
    Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
    Cc: Jens Axboe <axboe@kernel.dk>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    1a5f439c
page_io.c 10.4 KB