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[2003:cb:c701:d200:ee5d:1275:f171:136d]) by smtp.gmail.com with ESMTPSA id v16-20020a7bcb50000000b003942a244ee0sm2549625wmj.37.2022.05.12.06.37.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 12 May 2022 06:37:16 -0700 (PDT) Message-ID: Date: Thu, 12 May 2022 15:37:13 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH 06/15] mm/swap: remove buggy cache->nr check in refill_swap_slots_cache To: Miaohe Lin , akpm@linux-foundation.org Cc: willy@infradead.org, vbabka@suse.cz, dhowells@redhat.com, neilb@suse.de, apopple@nvidia.com, surenb@google.com, peterx@redhat.com, naoya.horiguchi@nec.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20220509131416.17553-1-linmiaohe@huawei.com> <20220509131416.17553-7-linmiaohe@huawei.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20220509131416.17553-7-linmiaohe@huawei.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: C37511C00BC X-Stat-Signature: 8g13wkao8g9d8uwa4qn4wp9nto146acx Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=i5WJr6QY; dmarc=pass (policy=none) header.from=redhat.com; spf=none (imf20.hostedemail.com: domain of david@redhat.com has no SPF policy when checking 170.10.129.124) smtp.mailfrom=david@redhat.com X-Rspam-User: X-HE-Tag: 1652362631-324679 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 09.05.22 15:14, Miaohe Lin wrote: > refill_swap_slots_cache is always called when cache->nr is 0. And if > cache->nr != 0, we should return cache->nr instead of 0. So remove > such buggy and confusing check. Not sure about the "cache->nr != 0, we should return cache->nr instead of 0" part, I'd just drop that from the patch description. We'd actually end up overwriting cache->nr after your change, which doesn't sound right and also different to what you describe here. > > Signed-off-by: Miaohe Lin > --- > mm/swap_slots.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/swap_slots.c b/mm/swap_slots.c > index 2f877e6f87d7..2a65a89b5b4d 100644 > --- a/mm/swap_slots.c > +++ b/mm/swap_slots.c > @@ -258,7 +258,7 @@ void enable_swap_slots_cache(void) > /* called with swap slot cache's alloc lock held */ > static int refill_swap_slots_cache(struct swap_slots_cache *cache) > { > - if (!use_swap_slot_cache || cache->nr) > + if (!use_swap_slot_cache) > return 0; > > cache->cur = 0; I feel like if this function would be called with cache->nr, it would be a BUG. So I'm fine with removing it, but we could also think about turning it into some sort of WARN/BG to make it clearer that this is unexpected. Anyhow, Acked-by: David Hildenbrand -- Thanks, David / dhildenb