• David Rientjes's avatar
    mm: add gfp flags for NODEMASK_ALLOC slab allocations · bad44b5b
    David Rientjes authored
    
    
    Objects passed to NODEMASK_ALLOC() are relatively small in size and are
    backed by slab caches that are not of large order, traditionally never
    greater than PAGE_ALLOC_COSTLY_ORDER.
    
    Thus, using GFP_KERNEL for these allocations on large machines when
    CONFIG_NODES_SHIFT > 8 will cause the page allocator to loop endlessly in
    the allocation attempt, each time invoking both direct reclaim or the oom
    killer.
    
    This is of particular interest when using NODEMASK_ALLOC() from a
    mempolicy context (either directly in mm/mempolicy.c or the mempolicy
    constrained hugetlb allocations) since the oom killer always kills current
    when allocations are constrained by mempolicies.  So for all present use
    cases in the kernel, current would end up being oom killed when direct
    reclaim fails.  That would allow the NODEMASK_ALLOC() to succeed but
    current would have sacrificed itself upon returning.
    
    This patch adds gfp flags to NODEMASK_ALLOC() to pass to kmalloc() on
    CONFIG_NODES_SHIFT > 8; this parameter is a nop on other configurations.
    All current use cases either directly from hugetlb code or indirectly via
    NODEMASK_SCRATCH() union __GFP_NORETRY to avoid direct reclaim and the oom
    killer when the slab allocator needs to allocate additional pages.
    
    The side-effect of this change is that all current use cases of either
    NODEMASK_ALLOC() or NODEMASK_SCRATCH() need appropriate -ENOMEM handling
    when the allocation fails (never for CONFIG_NODES_SHIFT <= 8).  All
    current use cases were audited and do have appropriate error handling at
    this time.
    Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
    Acked-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
    Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
    Cc: Mel Gorman <mel@csn.ul.ie>
    Cc: Randy Dunlap <randy.dunlap@oracle.com>
    Cc: Nishanth Aravamudan <nacc@us.ibm.com>
    Cc: Andi Kleen <andi@firstfloor.org>
    Cc: David Rientjes <rientjes@google.com>
    Cc: Adam Litke <agl@us.ibm.com>
    Cc: Andy Whitcroft <apw@canonical.com>
    Cc: Eric Whitney <eric.whitney@hp.com>
    Cc: Christoph Lameter <cl@linux-foundation.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    bad44b5b