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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=j6PJ67oAnfzV9PxkuyEMm7X3urH+VAUx7uNIfBIgK8A=; b=2H4ElFH+uuqQLONowGQYgb4MWgbL5hwNemMsntnCPgsBz7EWdruJn3YGG53pBaaK/7 /cWHr7pUmZas2voxvx7W6idMwx92wi172NMqGJwlxvtQC+ARZMIalswGOL+i+3HueFXr 9fjqXO2L45MtCOy03Cgn4UJh3wuWA8P3bY+V1dfFZ6UZNiGa2rOA5MOuMA1veOSMKDQw 3XHMmYV+K9e6QltCozxQt++/WNVBaUlhZr+x9XW+FEvaLO4THYsuEZMTrFOhQNStZUJZ 7ZvLNsDufAJsQm0XreosF/2jEhJs4rkoTy8yA29VtbsZ2VF/jQJ5Y8NGntnHGloAHHAO p0Wg== X-Gm-Message-State: AO0yUKUYOgUWdnChvWStNxmBvkOH1jDXeBrEWr/v//TSDv7JmL+msxHi AYRD6ME2b6gljTrIbXTw3aQgKcuelW/NI5RcNANWww== X-Google-Smtp-Source: AK7set8NIfHhdPuyL1RvDuayyrK39JHTj20Y7CDEMECMUkWmAbcHmsIgGk35BlpCcNAq5/QsmCjbLZ6FgKApKS2x2KE= X-Received: by 2002:a25:c247:0:b0:80b:6201:bee7 with SMTP id s68-20020a25c247000000b0080b6201bee7mr1062130ybf.340.1674694588781; Wed, 25 Jan 2023 16:56:28 -0800 (PST) MIME-Version: 1.0 References: <20230125233554.153109-1-surenb@google.com> <20230125233554.153109-3-surenb@google.com> <20230125162810.ec222773d13cd26c55991fde@linux-foundation.org> In-Reply-To: <20230125162810.ec222773d13cd26c55991fde@linux-foundation.org> From: Suren Baghdasaryan Date: Wed, 25 Jan 2023 16:56:17 -0800 Message-ID: Subject: Re: [PATCH v3 2/7] mm: introduce vma->vm_flags wrapper functions To: Andrew Morton Cc: michel@lespinasse.org, jglisse@google.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mgorman@techsingularity.net, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, peterz@infradead.org, ldufour@linux.ibm.com, paulmck@kernel.org, mingo@redhat.com, will@kernel.org, luto@kernel.org, songliubraving@fb.com, peterx@redhat.com, david@redhat.com, dhowells@redhat.com, hughd@google.com, bigeasy@linutronix.de, kent.overstreet@linux.dev, punit.agrawal@bytedance.com, lstoakes@gmail.com, peterjung1337@gmail.com, rientjes@google.com, axelrasmussen@google.com, joelaf@google.com, minchan@google.com, jannh@google.com, shakeelb@google.com, tatashin@google.com, edumazet@google.com, gthelen@google.com, gurua@google.com, arjunroy@google.com, soheil@google.com, hughlynch@google.com, leewalsh@google.com, posk@google.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: DC66F1C0003 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: cqw1haczk5q89hjq87mtwa51wnbwjxr7 X-HE-Tag: 1674694589-879138 X-HE-Meta: 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 FZPpXRvR 8zYHf+loWfJ2P2gGnq9XX1Zb/PNJMMkGFYEOHCrjYAHZYRYkM57KxhqScRVxnyOwgZyTWUBQ6V6QHLSiCG7uLer5vr+lhw6TKNKXtvW0TpoYCnAvq9b2fD5RiZwZVzTVTgMP4pjSPxFkTFdfRD0oQjEX2Njp6gJke4rT6ltZl5Lufw+IlZYjEMptstBKvs1nzCnoKPhNHLdwF1e5xUMwon3W78lDWRfnZMbjgK9lSUCXKmOzi2p6oyZie8HphpS/RMAeWJVPv4C9b+7+EnUnkQOnZksFjE2wOvg6VfwDDXkljo7MZlPudillcQKmIVSmaZQpKQdVyizTnU5S1uwGppFjNoXCs1X8hI25YMD+TwpF4gbHn1WO9jx7i6LTIkD/AuB18C2eMx+1QfNxXpuChxFJ2+TDVs35poKe63CR1kRahLJA= 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 Wed, Jan 25, 2023 at 4:28 PM Andrew Morton wrote: > > On Wed, 25 Jan 2023 15:35:49 -0800 Suren Baghdasaryan wrote: > > > --- a/include/linux/mm_types.h > > +++ b/include/linux/mm_types.h > > @@ -491,7 +491,15 @@ struct vm_area_struct { > > * See vmf_insert_mixed_prot() for discussion. > > */ > > pgprot_t vm_page_prot; > > - unsigned long vm_flags; /* Flags, see mm.h. */ > > + > > + /* > > + * Flags, see mm.h. > > + * To modify use {init|reset|set|clear|mod}_vm_flags() functions. > > + */ > > + union { > > + const vm_flags_t vm_flags; > > + vm_flags_t __private __vm_flags; > > + }; > > Typically when making a change like this we'll rename the affected > field/variable/function/etc. This will reliably and deliberately break > unconverted usage sites. > > This const trick will get us partway there, by breaking setters. But > renaming it will break both setters and getters. My intent here is to break setters but to allow getters to keep reading vma->vm_flags directly. We could provide get_vm_flags() and convert all getters as well but it would introduce a huge additional churn (800+ hits) with no obvious benefits, I think. Does that clarify the intent of this trick? > > -- > To unsubscribe from this group and stop receiving emails from it, send an email to kernel-team+unsubscribe@android.com. >