May I ask a newbie question? Say, there is some amount of memory pages which can be reclaimed if they are flushed to storage. And lower layer might issue memory allocation request in a way which won't cause reclaim deadlock (e.g. using GFP_NOFS or GFP_NOIO) when flushing to storage, isn't it?
What I'm worrying is a dependency that __GFP_FS allocation requests think that there are reclaimable pages and therefore there is no need to call out_of_memory(); and GFP_NOFS allocation requests which the __GFP_FS allocation requests depend on (in order to flush to storage) is waiting for GFP_NOIO allocation requests; and the GFP_NOIO allocation requests which the GFP_NOFS allocation requests depend on (in order to flush to storage) are waiting for memory pages to be reclaimed without calling out_of_memory(); because gfp_to_alloc_flags() does not favor GFP_NOIO over GFP_NOFS nor GFP_NOFS over __GFP_FS which will throttle all allocations at the same watermark level. How do we guarantee that GFP_NOFS/GFP_NOIO allocations make forward progress? What mechanism guarantees that memory pages which __GFP_FS allocation requests are waiting for are reclaimed? I assume that there is some mechanism; otherwise we can hit silent livelock, can't we? -- 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/
