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From: Baoquan He To: "Barry Song (Xiaomi)" Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, david@kernel.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, chrisl@kernel.org, kasong@tencent.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, youngjun.park@lge.com, jp.kobryn@linux.dev, usama.arif@linux.dev, shakeel.butt@linux.dev Subject: Re: [RFC PATCH 1/3] mm: avoid unnecessary lru drain for wp_can_reuse_anon_folio() Message-ID: References: <20260611105124.98668-1-baohua@kernel.org> <20260611105124.98668-2-baohua@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260611105124.98668-2-baohua@kernel.org> X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: A00441A0005 X-Stat-Signature: iahowcwuw8rscizm5y6gyg6bsa6rg4yz X-HE-Tag: 1781235678-809443 X-HE-Meta: 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 UXvmbhLw ZIeHB/dmm/u1dy+Anc+O6Aw1LC5WFtgM2p3UJZq1hqeDqtJRisCUW5nGcml2TVT3HItA/RD90Sj8gHuLZRYJGP0mBabSVNez3gd7IFhc1jiJ8ykD8LyeHaodovB4OxFx6EoaS4lr9I4hd/XVrKHJ7aQQf0vLMjpubCxNrHPNhi0eMai5ZK2Dyo+ElpARUuoIHIyINMzi4tIFHYiGaPB7UVP1fC6j7ijAHsrcgZtiIoHKtJACeC8gq7UHDMsLf45xr7aDsdPkqPW5lhmuzQL8xCaAPzd2n4GIsa4z0DVEZOjp24RU2O8QyLldyXg9EeYwYoEG1 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 06/11/26 at 06:51pm, Barry Song (Xiaomi) wrote: > We always unconditionally drain the LRU before retrying anon folio > reuse in wp_can_reuse_anon_folio(). Instead, assume !LRU anon folios > are in lru_cache, and use the refcount to avoid many unnecessary LRU > drains. > > Signed-off-by: Barry Song (Xiaomi) > --- > mm/memory.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/mm/memory.c b/mm/memory.c > index 56be920c56d7..487a34377a7b 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -4193,12 +4193,18 @@ static bool wp_can_reuse_anon_folio(struct folio *folio, > */ > if (folio_test_ksm(folio) || folio_ref_count(folio) > 3) > return false; > - if (!folio_test_lru(folio)) > + if (!folio_test_lru(folio)) { > + /* > + * Assume folio is on lru_cache and holds a cache reference. > + */ > + if (folio_ref_count(folio) > 2 + folio_test_swapcache(folio)) > + return false; > /* > * We cannot easily detect+handle references from > * remote LRU caches or references to LRU folios. > */ > lru_add_drain(); > + } > if (folio_ref_count(folio) > 1 + folio_test_swapcache(folio)) > return false; > if (!folio_trylock(folio)) Reviewed-by: Baoquan He > -- > 2.39.3 (Apple Git-146) >