From 84ad5802a33a4964a49b8f7d24d80a214a096b19 Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Thu, 14 Jan 2016 15:20:18 -0800 Subject: proc: meminfo: estimate available memory more conservatively The MemAvailable item in /proc/meminfo is to give users a hint of how much memory is allocatable without causing swapping, so it excludes the zones' low watermarks as unavailable to userspace. However, for a userspace allocation, kswapd will actually reclaim until the free pages hit a combination of the high watermark and the page allocator's lowmem protection that keeps a certain amount of DMA and DMA32 memory from userspace as well. Subtract the full amount we know to be unavailable to userspace from the number of free pages when calculating MemAvailable. Signed-off-by: Johannes Weiner Cc: Rik van Riel Cc: Mel Gorman Acked-by: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/meminfo.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) (limited to 'fs/proc') diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c index 9155a5a0d3b9..df4661abadc4 100644 --- a/fs/proc/meminfo.c +++ b/fs/proc/meminfo.c @@ -57,11 +57,8 @@ static int meminfo_proc_show(struct seq_file *m, void *v) /* * Estimate the amount of memory available for userspace allocations, * without causing swapping. - * - * Free memory cannot be taken below the low watermark, before the - * system starts swapping. */ - available = i.freeram - wmark_low; + available = i.freeram - totalreserve_pages; /* * Not all the page cache can be freed, otherwise the system will -- cgit v1.2.3-59-g8ed1b