mm/page_alloc.c: fix a misleading comment
The comment says that the per-cpu batchsize and zone watermarks are determined by present_pages which is definitely wrong, they are both calculated from managed_pages. Fix it. Signed-off-by: Yaowei Bai <bywxiaobai@163.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -349,7 +349,7 @@ zone[i]'s protection[j] is calculated by following expression.
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(i < j):
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zone[i]->protection[j]
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= (total sums of present_pages from zone[i+1] to zone[j] on the node)
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= (total sums of managed_pages from zone[i+1] to zone[j] on the node)
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/ lowmem_reserve_ratio[i];
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(i = j):
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(should not be protected. = 0;
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@ -360,7 +360,7 @@ The default values of lowmem_reserve_ratio[i] are
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256 (if zone[i] means DMA or DMA32 zone)
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32 (others).
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As above expression, they are reciprocal number of ratio.
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256 means 1/256. # of protection pages becomes about "0.39%" of total present
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256 means 1/256. # of protection pages becomes about "0.39%" of total managed
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pages of higher zones on the node.
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If you would like to protect more pages, smaller values are effective.
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@ -6022,7 +6022,7 @@ void __init mem_init_print_info(const char *str)
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* set_dma_reserve - set the specified number of pages reserved in the first zone
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* @new_dma_reserve: The number of pages to mark reserved
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*
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* The per-cpu batchsize and zone watermarks are determined by present_pages.
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* The per-cpu batchsize and zone watermarks are determined by managed_pages.
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* In the DMA zone, a significant percentage may be consumed by kernel image
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* and other unfreeable allocations which can skew the watermarks badly. This
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* function may optionally be used to account for unfreeable pages in the
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