Messages in this thread | | | Date | Thu, 14 Jul 2011 13:46:34 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [PATCH 1/5] mm: vmscan: Do not writeback filesystem pages in direct reclaim |
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On Thu, 14 Jul 2011 00:46:43 -0400 Christoph Hellwig <hch@infradead.org> wrote:
> On Thu, Jul 14, 2011 at 10:38:01AM +0900, KAMEZAWA Hiroyuki wrote: > > > + /* > > > + * Only kswapd can writeback filesystem pages to > > > + * avoid risk of stack overflow > > > + */ > > > + if (page_is_file_cache(page) && !current_is_kswapd()) { > > > + inc_zone_page_state(page, NR_VMSCAN_WRITE_SKIP); > > > + goto keep_locked; > > > + } > > > + > > > > > > This will cause tons of memcg OOM kill because we have no help of kswapd (now). > > XFS and btrfs already disable writeback from memcg context, as does ext4 > for the typical non-overwrite workloads, and none has fallen apart. > > In fact there's no way we can enable them as the memcg calling contexts > tend to have massive stack usage. >
Hmm, XFS/btrfs adds pages to radix-tree in deep stack ?
Thanks, -Kame
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