linux-kernel - Re: [PATCH] mm/gup: don't check page lru flag before draining it

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Date: Mon, 17 Jun 2024 19:22:59 +0800
From: yangge1116 <yangge1116@....com>
To: David Hildenbrand <david@...hat.com>, Matthew Wilcox <willy@...radead.org>
Cc: Baolin Wang <baolin.wang@...ux.alibaba.com>, 21cnbao@...il.com,
 akpm@...ux-foundation.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org,
 liuzixing@...on.cn
Subject: Re: [PATCH] mm/gup: don't check page lru flag before draining it



在 2024/6/17 下午5:52, David Hildenbrand 写道:
> Why would we want to make folio_maybe_dma_pinned() detection that worse

Just want to fix it using the existing function, seems a little 
unreasonable. I will prepare the V2 using folio_test_lru(folio) to check.

static unsigned long collect_longterm_unpinnable_pages(...)
{
...
     if (!folio_test_lru(folio) && drain_allow) {
         lru_add_drain_all();
         drain_allow = false;
     }
...
}

void folio_mark_lazyfree(struct folio *folio)
{
     if (folio_test_anon(folio) && folio_test_swapbacked(folio) &&
        !folio_test_swapcache(folio) && !folio_test_unevictable(folio)) {
         struct folio_batch *fbatch;

         folio_get(folio);
         if (!folio_test_clear_lru(folio)) {
             folio_put(folio);
             return;
         }

         local_lock(&cpu_fbatches.lock);
         fbatch = this_cpu_ptr(&cpu_fbatches.lru_lazyfree);
         folio_batch_add_and_move(fbatch, folio, lru_lazyfree_fn);
         local_unlock(&cpu_fbatches.lock);
     }
}