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b=Nf8cEsUY6l4N1GQ18fTWQsQFh0KEOFmRVygqi7Pd/aVo0tbVvp0RYxAOg6RNvQFqE NcoZhf0FgoeX+tO/jdkIWGfVWuGDor7dxXcXZmU8Td0EPFZqASTVMPotp9BszbNKd6 uno05vQuD3bB34Eb/w/gD/BfWAIg9pK0z5KTxHSm6MxIYG4ACzoIzmP8cjwcTXIYvP LU6b2IYUssfZXnBVJvGv/q7JnzcNaaBh7PesdBPITJsvgHV0jR5bB4nFU6hd7b40ah ThWJhjJ4sf+QhGyNF4n7QFmbFMOkakaQDfZjdbJrYe1YSisNlt0fHTgtlB7tbtekjJ UUmMGxu2nnvDg== Message-ID: Date: Wed, 24 Jun 2026 17:02:12 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/4] mm: avoid unnecessary lru drain for wp_can_reuse_anon_folio() To: "Barry Song (Xiaomi)" , akpm@linux-foundation.org, linux-mm@kvack.org Cc: baoquan.he@linux.dev, chrisl@kernel.org, jp.kobryn@linux.dev, kasong@tencent.com, liam@infradead.org, linux-kernel@vger.kernel.org, ljs@kernel.org, mhocko@suse.com, nphamcs@gmail.com, rppt@kernel.org, shakeel.butt@linux.dev, shikemeng@huaweicloud.com, surenb@google.com, usama.arif@linux.dev, vbabka@kernel.org, youngjun.park@lge.com References: <20260623231635.43086-1-baohua@kernel.org> <20260623231635.43086-2-baohua@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: dyp6h9opc3ojps4dsxyq6esjuhc6uxy4 X-Rspamd-Queue-Id: E131AC0016 X-Rspam-User: X-Rspamd-Server: rspam01 X-HE-Tag: 1782313339-446871 X-HE-Meta: U2FsdGVkX1/DEzq8yFaF99TS8BrmY9OmjW8ReavnZpyvUX66JJNiQxJlBCgQPWfS4NI+F4aGUV4s9UM7QiXcBMuEAt1GK8EbeZSiWSuRcKi252N0iI2qbX09pEo6T00v7CZmFygUiFLZF8vrVFjwotgeC8MpFZtEIDuisrvuDlJ6Kxiiz+AUf14fqIXInzp1g1GKPagi79Fb4s6SE8e5Xk18at8hRQh37B230VxGI1AsxGKx/yzb+SqMdtFkkjB7DjtnwppHkLzynCWzMZV39DJ70pl2undXjTU+lS7DcNRc/I5gSyHJRqLTAdnmjKjKwd2XJs0vsHr5TAPEEx7vTTErUYv2MJMkhEbwf39sNrime8HSmKa/eQAF3uTxZ7BIsDW02R8gQRgm1tW8qfkEmeArHzSD5lvdzJixqR3GBnb0GqUM/fd7O+PElBLRmoPGoERSkMMiBFM4wkyVL3ASoVA/FB2zdaq68BVVypgDlgE4lbirlrQSX1A6l3Ikpy9SiXaKH60mhVRYChiUB1pgDdM83PSQTw1TJeWNFLQStk3zoYXpFXi8LJlaw3cgNZk4EBZAQwLXykTLVtkSsmwEYG0/XENpgbATBNUblkJ8N9r8wh87NpjgKAUPYYHTITVDl5GJD6RBSk6KNknOzjG66YYjwxOybvpuAUtZC6D5mnL5EPuMGN46Pc6jfosWG0oa2yVdrtCt0n3EYb3f3w0qU4BDdFEJfjjr5BHbCLHdZ5Uy/JgTAM0uw1a55N66KVkruyPQ0gXAlW8tH76msV2Gwk3HFVTIjS9HTs66PteRCV7eqjbA3lK4AeT0BNWOabd2C7//K5XEszz1KrBWd3/Fkb1PUNyxTm+5mvArbluQmv5gjjlplEjO+Vuq7EJUb33ATGdNFDbIY53qI/7pSnbe5ZyDAMK1uaJTQb79PtcGc/fUjy6iD9NO7Xe9pTRUwMDqhB80eObN7rhPgzhr1qJ eqOFiuB/ RxDj0nbbTy7qo9KKECD/cNaVq2W0BRXDxzDjY8cfbN1qLVtzgO2zxBDgULLM9oL+vDE/2CQZNgnIzCE9HPX5jlwWY4iT7MgNLzXf8UuvaBUm5gTarxeX9oItsqXLwiTO1sdevgJ5bbwOKx2HnkcOP/D0B5a35AivOLB9U9ucZaXHb+fw5a4iFx++9I/PK2d6/TqIpkGTMjEd1aL7vl+kNjh9JMyul7xsccckZaECUYzuNU3WrLHj1IZJu8kjeRUMuUdN69DKIP5258HNFQqp1vdAGorI/CqGVgb6l/3E3t2UAqWhmJcClbxZQUKIMV0ESG+6RlE5gF2UplOA= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 6/24/26 01:16, 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. > > Acked-by: Shakeel Butt > Reviewed-by: Baoquan He > 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 ff338c2abe92..f6848f4234a6 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; I'm not keen on making this function even uglier, so no, not like that. We have the earlier "folio_ref_count(folio) > 3" check. In which scenarios can you trigger this such that we would care? If the answer is "I don't know" there is no reason for a change. -- Cheers, David