mm/page_alloc.c: reset numa stats for boot pagesets
Initially, the per-cpu pagesets of each zone are set to the boot pagesets. The real pagesets are allocated later but before that happens, page allocations do occur and the numa stats for the boot pagesets get incremented since they are common to all zones at that point. The real pagesets, however, are allocated for the populated zones only. Unpopulated zones, like those associated with memory-less nodes, continue using the boot pageset and end up skewing the numa stats of the corresponding node. E.g. $ numactl -H available: 2 nodes (0-1) node 0 cpus: 0 1 2 3 node 0 size: 0 MB node 0 free: 0 MB node 1 cpus: 4 5 6 7 node 1 size: 8131 MB node 1 free: 6980 MB node distances: node 0 1 0: 10 40 1: 40 10 $ numastat node0 node1 numa_hit 108 56495 numa_miss 0 0 numa_foreign 0 0 interleave_hit 0 4537 local_node 108 31547 other_node 0 24948 Hence, the boot pageset stats need to be cleared after the real pagesets are allocated. After this point, the stats of the boot pagesets do not change as page allocations requested for a memory-less node will either fail (if __GFP_THISNODE is used) or get fulfilled by a preferred zone of a different node based on the fallback zonelist. [sandipan@linux.ibm.com: v3] Link: http://lkml.kernel.org/r/20200511170356.162531-1-sandipan@linux.ibm.com Signed-off-by:Sandipan Das <sandipan@linux.ibm.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Acked-by:
Vlastimil Babka <vbabka@suse.cz> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Michal Hocko <mhocko@suse.com> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Link: http://lkml.kernel.org/r/9c9c2d1b15e37f6e6bf32f99e3100035e90c4ac9.1588868430.git.sandipan@linux.ibm.com Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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