• Vlastimil Babka's avatar
    mm: rename alloc_pages_exact_node() to __alloc_pages_node() · 96db800f
    Vlastimil Babka authored
    alloc_pages_exact_node() was introduced in commit 6484eb3e ("page
    allocator: do not check NUMA node ID when the caller knows the node is
    valid") as an optimized variant of alloc_pages_node(), that doesn't
    fallback to current node for nid == NUMA_NO_NODE.  Unfortunately the
    name of the function can easily suggest that the allocation is
    restricted to the given node and fails otherwise.  In truth, the node is
    only preferred, unless __GFP_THISNODE is passed among the gfp flags.
    The misleading name has lead to mistakes in the past, see for example
    commits 5265047a ("mm, thp: really limit transparent hugepage
    allocation to local node") and b360edb4 ("mm, mempolicy:
    migrate_to_node should only migrate to node").
    Another issue with the name is that there's a family of
    alloc_pages_exact*() functions where 'exact' means exact size (instead
    of page order), which leads to more confusion.
    To prevent further mistakes, this patch effectively renames
    alloc_pages_exact_node() to __alloc_pages_node() to better convey that
    it's an optimized variant of alloc_pages_node() not intended for general
    usage.  Both functions get described in comments.
    It has been also considered to really provide a convenience function for
    allocations restricted to a node, but the major opinion seems to be that
    __GFP_THISNODE already provides that functionality and we shouldn't
    duplicate the API needlessly.  The number of users would be small
    Existing callers of alloc_pages_exact_node() are simply converted to
    call __alloc_pages_node(), with the exception of sba_alloc_coherent()
    which open-codes the check for NUMA_NO_NODE, so it is converted to use
    alloc_pages_node() instead.  This means it no longer performs some
    VM_BUG_ON checks, and since the current check for nid in
    alloc_pages_node() uses a 'nid < 0' comparison (which includes
    NUMA_NO_NODE), it may hide wrong values which would be previously
    Both differences will be rectified by the next patch.
    To sum up, this patch makes no functional changes, except temporarily
    hiding potentially buggy callers.  Restricting the checks in
    alloc_pages_node() is left for the next patch which can in turn expose
    more existing buggy callers.
    Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
    Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
    Acked-by: default avatarRobin Holt <robinmholt@gmail.com>
    Acked-by: default avatarMichal Hocko <mhocko@suse.com>
    Acked-by: default avatarChristoph Lameter <cl@linux.com>
    Acked-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    Cc: Mel Gorman <mgorman@suse.de>
    Cc: David Rientjes <rientjes@google.com>
    Cc: Greg Thelen <gthelen@google.com>
    Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
    Cc: Pekka Enberg <penberg@kernel.org>
    Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
    Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
    Cc: Tony Luck <tony.luck@intel.com>
    Cc: Fenghua Yu <fenghua.yu@intel.com>
    Cc: Arnd Bergmann <arnd@arndb.de>
    Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    Cc: Paul Mackerras <paulus@samba.org>
    Cc: Gleb Natapov <gleb@kernel.org>
    Cc: Paolo Bonzini <pbonzini@redhat.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: "H. Peter Anvin" <hpa@zytor.com>
    Cc: Cliff Whickman <cpw@sgi.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
slob.c 16 KB