• Miao Xie's avatar
    cpuset,mm: fix no node to alloc memory when changing cpuset's mems · c0ff7453
    Miao Xie authored
    Before applying this patch, cpuset updates task->mems_allowed and
    mempolicy by setting all new bits in the nodemask first, and clearing all
    old unallowed bits later.  But in the way, the allocator may find that
    there is no node to alloc memory.
    The reason is that cpuset rebinds the task's mempolicy, it cleans the
    nodes which the allocater can alloc pages on, for example:
    (mpol: mempolicy)
    	task1			task1's mpol	task2
    	alloc page		1
    	  alloc on node0? NO	1
    				1		change mems from 1 to 0
    				1		rebind task1's mpol
    				0-1		  set new bits
    				0	  	  clear disallowed bits
    	  alloc on node1? NO	0
    	can't alloc page
    	  goto oom
    This patch fixes this problem by expanding the nodes range first(set newly
    allowed bits) and shrink it lazily(clear newly disallowed bits).  So we
    use a variable to tell the write-side task that read-side task is reading
    nodemask, and the write-side task clears newly disallowed nodes after
    read-side task ends the current memory allocation.
    [akpm@linux-foundation.org: fix spello]
    Signed-off-by: default avatarMiao Xie <miaox@cn.fujitsu.com>
    Cc: David Rientjes <rientjes@google.com>
    Cc: Nick Piggin <npiggin@suse.de>
    Cc: Paul Menage <menage@google.com>
    Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
    Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
    Cc: Ravikiran Thirumalai <kiran@scalex86.org>
    Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
    Cc: Christoph Lameter <cl@linux-foundation.org>
    Cc: Andi Kleen <andi@firstfloor.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
slub.c 110 KB