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Sat, 28 Aug 2021 09:19:48 -0700 (PDT) Received: from grain.localdomain ([5.18.253.97]) by smtp.gmail.com with ESMTPSA id w3sm1113472ljm.13.2021.08.28.09.19.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 28 Aug 2021 09:19:47 -0700 (PDT) Received: by grain.localdomain (Postfix, from userid 1000) id AC9EF5A001E; Sat, 28 Aug 2021 19:19:46 +0300 (MSK) Date: Sat, 28 Aug 2021 19:19:46 +0300 From: Cyrill Gorcunov To: Suren Baghdasaryan Cc: akpm@linux-foundation.org, ccross@google.com, sumit.semwal@linaro.org, mhocko@suse.com, dave.hansen@intel.com, keescook@chromium.org, willy@infradead.org, kirill.shutemov@linux.intel.com, vbabka@suse.cz, hannes@cmpxchg.org, corbet@lwn.net, viro@zeniv.linux.org.uk, rdunlap@infradead.org, kaleshsingh@google.com, peterx@redhat.com, rppt@kernel.org, peterz@infradead.org, catalin.marinas@arm.com, vincenzo.frascino@arm.com, chinwen.chang@mediatek.com, axelrasmussen@google.com, aarcange@redhat.com, jannh@google.com, apopple@nvidia.com, jhubbard@nvidia.com, yuzhao@google.com, will@kernel.org, fenghua.yu@intel.com, thunder.leizhen@huawei.com, hughd@google.com, feng.tang@intel.com, jgg@ziepe.ca, guro@fb.com, tglx@linutronix.de, krisman@collabora.com, chris.hyser@oracle.com, pcc@google.com, ebiederm@xmission.com, axboe@kernel.dk, legion@kernel.org, eb@emlix.com, songmuchun@bytedance.com, viresh.kumar@linaro.org, thomascedeno@google.com, sashal@kernel.org, cxfcosmos@gmail.com, linux@rasmusvillemoes.dk, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, kernel-team@android.com, Pekka Enberg , Ingo Molnar , Oleg Nesterov , Jan Glauber , John Stultz , Rob Landley , "Serge E. Hallyn" , David Rientjes , Rik van Riel , Mel Gorman , Michel Lespinasse , Tang Chen , Robin Holt , Shaohua Li , Sasha Levin , Minchan Kim Subject: Re: [PATCH v8 1/3] mm: rearrange madvise code to allow for reuse Message-ID: References: <20210827191858.2037087-1-surenb@google.com> <20210827191858.2037087-2-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210827191858.2037087-2-surenb@google.com> User-Agent: Mutt/2.0.7 (2021-05-04) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=gmail.com header.s=20161025 header.b=u+8fDKLk; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf01.hostedemail.com: domain of gorcunov@gmail.com designates 209.85.167.49 as permitted sender) smtp.mailfrom=gorcunov@gmail.com X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 107E45034DD6 X-Stat-Signature: mzbgthjx7zm8eqjymcko3m6uy9r1nu4f X-HE-Tag: 1630167589-688758 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 Fri, Aug 27, 2021 at 12:18:56PM -0700, Suren Baghdasaryan wrote: ... > > +/* > + * Apply an madvise behavior to a region of a vma. madvise_update_vma > + * will handle splitting a vm area into separate areas, each area with its own > + * behavior. > + */ > +static int madvise_vma_behavior(struct vm_area_struct *vma, > + struct vm_area_struct **prev, > + unsigned long start, unsigned long end, > + unsigned long behavior) > +{ > + int error = 0; Hi Suren! A nitpick -- this variable is never used with default value so I think we could drop assignment here. ... > + case MADV_DONTFORK: > + new_flags |= VM_DONTCOPY; > + break; > + case MADV_DOFORK: > + if (vma->vm_flags & VM_IO) { > + error = -EINVAL; We can exit early here, without jumping to the end of the function, right? > + goto out; > + } > + new_flags &= ~VM_DONTCOPY; > + break; > + case MADV_WIPEONFORK: > + /* MADV_WIPEONFORK is only supported on anonymous memory. */ > + if (vma->vm_file || vma->vm_flags & VM_SHARED) { > + error = -EINVAL; And here too. > + goto out; > + } > + new_flags |= VM_WIPEONFORK; > + break; > + case MADV_KEEPONFORK: > + new_flags &= ~VM_WIPEONFORK; > + break; > + case MADV_DONTDUMP: > + new_flags |= VM_DONTDUMP; > + break; > + case MADV_DODUMP: > + if (!is_vm_hugetlb_page(vma) && new_flags & VM_SPECIAL) { > + error = -EINVAL; Same. > + goto out; > + } > + new_flags &= ~VM_DONTDUMP; > + break; > + case MADV_MERGEABLE: > + case MADV_UNMERGEABLE: > + error = ksm_madvise(vma, start, end, behavior, &new_flags); > + if (error) > + goto out; > + break; > + case MADV_HUGEPAGE: > + case MADV_NOHUGEPAGE: > + error = hugepage_madvise(vma, &new_flags, behavior); > + if (error) > + goto out; > + break; > + } > + > + error = madvise_update_vma(vma, prev, start, end, new_flags); > + > +out: I suppose we better keep the former comment on why we maps ENOMEM to EAGAIN? Cyrill