On 05/29/2015 08:55 AM, Michal Hocko wrote: > On Thu 28-05-15 12:59:34, Andrew Morton wrote: >> On Thu, 28 May 2015 20:26:06 +0300 Vladimir Davydov <vdavy...@parallels.com> >> wrote: >> >> > When trimming memcg consumption excess (see memory.high), we call >> > try_to_free_mem_cgroup_pages without checking if we are allowed to sleep >> > in the current context, which can result in a deadlock. Fix this. >> >> Why does it deadlock? try_to_free_mem_cgroup_pages() is passed the >> gfp_mask and should honour its __GFP_WAIT setting? > > The only instance of __GFP_WAIT check in vmscan code is in zone_reclaim. > Page allocations and memcg reclaim avoids calling reclaim if __GFP_WAIT > is not set. Maybe we can move the check to do_try_to_free_pages?
I think it's conceptually wrong. All other paths check it before calling into do_try_to_free_pages() and act appropriately. Here it would potentially mask any atomic-specific fallback strategy. What would make some sense in do_try_to_free_pages() is VM_WARN_ON_ONCE() which however I assume doesn't exist? :) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
