• Naoya Horiguchi's avatar
    mm: hwpoison: drop lru_add_drain_all() in __soft_offline_page() · 9ab3b598
    Naoya Horiguchi authored
    A race condition starts to be visible in recent mmotm, where a PG_hwpoison
    flag is set on a migration source page *before* it's back in buddy page
    poo= l.
    
    This is problematic because no page flag is supposed to be set when
    freeing (see __free_one_page().) So the user-visible effect of this race
    is that it could trigger the BUG_ON() when soft-offlining is called.
    
    The root cause is that we call lru_add_drain_all() to make sure that the
    page is in buddy, but that doesn't work because this function just
    schedule= s a work item and doesn't wait its completion.
    drain_all_pages() does drainin= g directly, so simply dropping
    lru_add_drain_all() solves this problem.
    
    Fixes: f15bdfa8 ("mm/memory-failure.c: fix memory leak in successful soft offlining")
    Signed-off-by: 's avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
    Cc: Andi Kleen <andi@firstfloor.org>
    Cc: Tony Luck <tony.luck@intel.com>
    Cc: Chen Gong <gong.chen@linux.intel.com>
    Cc: <stable@vger.kernel.org>	[3.11+]
    Signed-off-by: 's avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
    9ab3b598
memory-failure.c 47.6 KB