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[86.164.169.89]) by smtp.gmail.com with ESMTPSA id r17-20020a05600c459100b003dee8c5d814sm3757706wmo.24.2023.02.01.23.17.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 Feb 2023 23:17:49 -0800 (PST) Date: Thu, 2 Feb 2023 07:17:48 +0000 From: Lorenzo Stoakes To: Baoquan He Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, stephen.s.brennan@oracle.com, urezki@gmail.com, willy@infradead.org, hch@infradead.org, error27@gmail.com Subject: Re: [PATCH v4 3/7] mm/vmalloc.c: allow vread() to read out vm_map_ram areas Message-ID: References: <20230201091339.61761-1-bhe@redhat.com> <20230201091339.61761-4-bhe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: C456B1C000A X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: kipkh99keae9gjdm6b8h8q9pryw5hpwt X-HE-Tag: 1675322271-448675 X-HE-Meta: U2FsdGVkX199y4efltkwkvkadDs28KSAdOlU39rKBPTgIMh70Xp3kzMqlVoNUguMdGisPLLoZlwmJlLbYF5qHIl9b201tA6En4+DHXw/vfKCu88VTcr08bi9MXWjrb9xi2xNzyr0tM9eblsh51M0IO+LDIHx5rFcUFdhUDVWQbwaVVDWZyNSyK6g3PfKR2u0eBonXKaxEBIAaenaxBjyuUgGZmG2n5GlgeJEIy+359CAjHXMvMTFS/GAW4JglindoBZOaIwXVC5y+stFEpKW63Frs+AFlEKj7hXLpcLE1z4Bzk1nNvLUjr3CmHX8/J2sayLRKpfkLof0GCpwq7r5ufNv/QuDNrADNJyvRakItD2/qyXwXGGUMivcVTqIpL7TsYo6Pia7pXLr8+EIIVgjDP/lCxrDWjZ+E6lZ+StmKqAm4EinpzCGOzhqT1ZvqxLvPG88RYbwYg+XkYD5JieseEAaAYr0gMMDCl/TIVj+70Tn1lT5dI0chUWcz/pme3pdKP3JkfMk9971OtlocxMVfb6nB+7pqKg2FQTdIRMwnHBjma3Rmtiqkmw/4xMwn9WZ/R4nqs8RjJMLhfmHsPck6olJ8/V0ey8kuWuFTVzLUj2Kv6Jx3gClPvNAv6bkKN14s4f9/j/kCQl22VCjJdmTU/MLS3x0yHN1yhw1fnhflg4/6joDPmbCOTgMxV/iDUdfvzsKtkorbUUP34TONj4CLdqVwLoeQbjWe99ne2BEGR59SAejK/Y2rlE/K0oZllVwlJAjm3IE1oN6zFIsE6AzfWChq+lYe/ZPz68RfJgdFjGtzkuLu5mbR91Vx9D4HcXYH6+1zN6pn1HSfN5PTluJgFGcWYvPOdaOUHWf4n7IRMRm4rjqxE7BYt7zOP0wS3GVv5AlA7oUT7wt6YO/pj+vViZpOQHl45/D6honP35AfTtmSlxWgcEOkRsN9ufpAIDdQ141D28PA5EfzPP4PNM RTV1mDnm GPkjAj5I//Z99UKPfOJLl8QnXTuZsKbKzxjVlWYCTJ+Y1M1T6IMjd+Y6wcb2uaPcmqL1f/7SwZpEEbknktlNbv1bJLGGP7KfVOsg2EMK0i+enBdk6l1YlDFnS91qw0z11Kgu+ZKOH0C3ZW+nignZ9XcmYHd/h3wK8D9vREdlo8kfSrpb4BuAWJ2G/adyw6dTw5vB3rigxF97SPrRUWLiBvkYyZf3SxHz14G2tBm4aW56XjxSPVwsqeIHG4O51TVsICjgpz+e+aSWryDpvzTNWwD/39mTlq0IKMNd2hXO7+qzLwQiyF3u/mMB2MSBd6JA/KQUHZD2zk82TTVwfdZqAOv088HqKBz5b72JzBwKtxuQpMr3L6h1yXRd/rejqX1rFsKR8DCZT/SmHfxA82jgelXOXfwZz1IDQixI+YEFrbJkmd6OC6iIMZzTSXEQP/NR5Edu1hjwjzNZatn9eXGEQcyWXnocB6CRGjj5UlEkfPId3Its= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000141, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Feb 02, 2023 at 11:20:07AM +0800, Baoquan He wrote: [snip] > > > + for_each_set_bitrange(rs, re, vb->used_map, VMAP_BBMAP_BITS) { > > > + if (!count) > > > + break; > > > + start = vmap_block_vaddr(vb->va->va_start, rs); > > > + while (addr < start) { > > > + if (count == 0) > > > + break; > > > > Bit pedantic, but you're using the `if (!count)` form of checking whether it's > > zero above, but here you explicitly check it, would be good to keep both consistent. > > Yeah, sounds good. Will change. > > > > > Given you're checking here, perhaps you could simply drop the previous check? > > Well, maybe no. The previous "if (!count)" is checking if count is 0 > after the 'count -=n;' line at the end of the for_each loop. While this > "if (count == 0)" is checking if count is 0 after 'count--;' at the end > of while loop. Not sure if I got your point. You're right, sorry each break is for a different loop :) and I guess the inner check is feeding the outer one so we're all good.