From: Andrea Arcangeli Date: Thu, 6 Jul 2017 22:37:02 +0000 (-0700) Subject: ksm: cleanup stable_node chain collapse case X-Git-Tag: v4.13-rc1~121^2~75 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=0ba1d0f7c41cdab306a3d30e036bc393c3ebba7e;hp=0ba1d0f7c41cdab306a3d30e036bc393c3ebba7e;p=linux.git ksm: cleanup stable_node chain collapse case Patch series "KSMscale cleanup/optimizations". There are no fixes here it's just minor cleanups and optimizations. 1/3 removes makes the "fix" for the stale stable_node fall in the standard case without introducing new cases. Setting stable_node to NULL was marginally safer, but stale pointer is still wiped from the caller, this looks cleaner. 2/3 should fix the false positive from Dan's static checker. 3/3 is a microoptimization to apply the the refile of future merge candidate dups at the head of the chain in all cases and to skip it in one case where we did it and but it was a noop (to avoid checking if it was already at the head but now we've to check it anyway so it got optimized away). This patch (of 3): When the stable_node chain is collapsed we can as well set the caller stable_node to match the returned stable_node_dup in chain_prune(). This way the collapse case becomes indistinguishable from the regular stable_node case and we can remove two branches from the KSM page migration handling slow paths. While it was all correct this looks cleaner (and faster) as the caller has to deal with fewer special cases. Link: http://lkml.kernel.org/r/20170518173721.22316-2-aarcange@redhat.com Signed-off-by: Andrea Arcangeli Cc: Evgheni Dereveanchin Cc: Andrey Ryabinin Cc: Petr Holasek Cc: Hugh Dickins Cc: Arjan van de Ven Cc: Davidlohr Bueso Cc: Gavin Guo Cc: Jay Vosburgh Cc: Mel Gorman Cc: Dan Carpenter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds ---