On Tue, 14 Feb 2012 13:09:55 +0000 Mel Gorman <mel@xxxxxxxxx> wrote: > Stuart Foster reported on https://bugzilla.kernel.org/show_bug.cgi?id=42578 > that copying large amounts of data from NTFS caused an OOM kill on 32-bit > X86 with 16G of memory. Andrew Morton correctly identified that the problem > was NTFS was using 512 blocks meaning each page had 8 buffer_heads in low > memory pinning it. > > In the past, direct reclaim used to scan highmem even if the allocating > process did not specify __GFP_HIGHMEM but not any more. kswapd no longer > will reclaim from zones that are above the high watermark. The intention > in both cases was to minimise unnecessary reclaim. The downside is on > machines with large amounts of highmem that lowmem can be fully consumed > by buffer_heads with nothing trying to free them. > > The following patch is based on a suggestion by Andrew Morton to extend > the buffer_heads_over_limit case to force kswapd and direct reclaim to > scan the highmem zone regardless of the allocation request or > watermarks. Seems reasonable, thanks. I wonder if we really needed to change balance_pdgat(). The smaller we can make profile of the special-case-hack the better. Perhaps poking it into direct reclaim was sufficient? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>