Messages in this thread | | | Date | Thu, 25 Jun 2020 14:40:17 +0200 | From | Michal Hocko <> | Subject | Re: [PATCH 6/6] mm: Add memalloc_nowait |
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On Thu 25-06-20 12:31:22, Matthew Wilcox wrote: > Similar to memalloc_noio() and memalloc_nofs(), memalloc_nowait() > guarantees we will not sleep to reclaim memory. Use it to simplify > dm-bufio's allocations.
memalloc_nowait is a good idea! I suspect the primary usecase would be vmalloc.
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
[...] > @@ -877,7 +857,9 @@ static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client > */ > while (1) { > if (dm_bufio_cache_size_latch != 1) { > - b = alloc_buffer(c, GFP_NOWAIT | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); > + unsigned nowait_flag = memalloc_nowait_save(); > + b = alloc_buffer(c, GFP_KERNEL | __GFP_NOMEMALLOC | __GFP_NOWARN); > + memalloc_nowait_restore(nowait_flag);
This looks confusing though. I am not familiar with alloc_buffer and there is quite some tweaking around __GFP_NORETRY in alloc_buffer_data which I do not follow but GFP_KERNEL just struck my eyes. So why cannot we have alloc_buffer(GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN); -- Michal Hocko SUSE Labs
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