3.16.72-rc1 review patch. If anyone has any objections, please let me know.
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From: Johannes Weiner hannes@cmpxchg.org
commit 84ad5802a33a4964a49b8f7d24d80a214a096b19 upstream.
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 hannes@cmpxchg.org Cc: Rik van Riel riel@redhat.com Cc: Mel Gorman mgorman@suse.de Acked-by: Michal Hocko mhocko@suse.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Ben Hutchings ben@decadent.org.uk --- fs/proc/meminfo.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)
--- a/fs/proc/meminfo.c +++ b/fs/proc/meminfo.c @@ -57,11 +57,8 @@ static int meminfo_proc_show(struct seq_ /* * 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