mm: move PageDoubleMap bit
Patch series "Fix PageDoubleMap". This is a purely theoretical problem for now as none of the filesystems which use PG_private_2 (ie PG_fscache) are being converted at this time, but it's confusing to leave it like this. This patch (of 2): PG_private_2 is defined as being PF_ANY (applicable to tail pages as well as regular & head pages). That means that the first tail page of a double-map page will appear to have Private2 set. Use the Workingset bit instead which is defined as PF_HEAD so any attempt to access the Workingset bit on a tail page will redirect to the head page's Workingset bit. Signed-off-by: NMatthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Reviewed-by: NZi Yan <ziy@nvidia.com> Link: https://lkml.kernel.org/r/20200629151933.15671-1-willy@infradead.org Link: https://lkml.kernel.org/r/20200629151933.15671-2-willy@infradead.orgSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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