Messages in this thread Patch in this message | | | Date | Thu, 25 Aug 2022 10:34:18 +0800 | Subject | Re: [PATCH 2/2] mm: slince possible data races about pgdat->kswapd | From | Kefeng Wang <> |
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On 2022/8/24 16:24, David Hildenbrand wrote: > On 24.08.22 09:19, Kefeng Wang wrote: >> The pgdat->kswapd could be accessed concurrently by kswapd_run() and >> kcompactd(), it don't be protected by any lock, which could leads to >> data races, adding READ/WRITE_ONCE() to slince it. > Okay, I think this patch here makes it clearer that we really just want > proper synchronization instead of hacking around it. > > What speaks against protecting pgdat->kswapd this using some proper > locking primitive?
as comments about kswapd in struct pglist_data, pgdat->kswapd should be
protected by mem_hotplug_begin/done(), how about this way?
diff --git a/mm/compaction.c b/mm/compaction.c index 640fa76228dd..62018f35242a 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1983,7 +1983,13 @@ static inline bool is_via_compact_memory(int order)
static bool kswapd_is_running(pg_data_t *pgdat) { - return pgdat->kswapd && task_is_running(pgdat->kswapd); + bool running; + + mem_hotplug_begin(); + running = pgdat->kswapd && task_is_running(pgdat->kswapd); + mem_hotplug_end(); + + return running; }
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