mm, fault_around: do not take a reference to a locked page
filemap_map_pages takes a speculative reference to each page in the range before it tries to lock that page. While this is correct it also can influence page migration which will bail out when seeing an elevated reference count. The faultaround code would bail on seeing a locked page so we can pro-actively check the PageLocked bit before page_cache_get_speculative and prevent from pointless reference count churn. Link: http://lkml.kernel.org/r/20181211142741.2607-4-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com> Suggested-by: NJan Kara <jack@suse.cz> Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: NDavid Hildenbrand <david@redhat.com> Acked-by: NHugh Dickins <hughd@google.com> Reviewed-by: NWilliam Kucharski <william.kucharski@oracle.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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