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Wed, 1 Sep 2021 08:09:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1630483765; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=DdzSE7BCCcPraxiLuEKrcJ+XK47RRhp4XBmGdfag4no=; b=OfTL8XUorxFNEHyBlAvuoICTsf3IdOGyj9zaWeFE8z4xH/SeYsvC5Z6ZgNebhVDgLaWtCq eHrPUyaNE16I+TcePG+D/bXPhPgWsrq/gvIwRz/TgBmwtNmTUPZEewEhs7P8cT7akxZmzY FpDSq7uWpc5mBkOp9XmJchBYvpUf0XI= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 3A7FBA3BA5; Wed, 1 Sep 2021 08:09:24 +0000 (UTC) Date: Wed, 1 Sep 2021 10:09:20 +0200 From: Michal Hocko To: Suren Baghdasaryan Cc: akpm@linux-foundation.org, ccross@google.com, sumit.semwal@linaro.org, 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 Subject: Re: [PATCH v8 2/3] mm: add a field to store names for private anonymous memory Message-ID: References: <20210827191858.2037087-1-surenb@google.com> <20210827191858.2037087-3-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210827191858.2037087-3-surenb@google.com> Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=OfTL8XUo; spf=pass (imf22.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.29 as permitted sender) smtp.mailfrom=mhocko@suse.com; dmarc=pass (policy=quarantine) header.from=suse.com X-Stat-Signature: axx6xprq5cku5p4eiuihhaxcisf65a1i X-Rspamd-Queue-Id: D545D1901 X-Rspamd-Server: rspam04 X-HE-Tag: 1630483766-400064 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 27-08-21 12:18:57, Suren Baghdasaryan wrote: [...] > Userspace can set the name for a region of memory by calling > prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, start, len, (unsigned long)name); > Setting the name to NULL clears it. Maybe I am missing this part but I do not see this being handled anywhere. [...] > @@ -3283,5 +3283,16 @@ static inline int seal_check_future_write(int seals, struct vm_area_struct *vma) > return 0; > } > > +#ifdef CONFIG_ADVISE_SYSCALLS > +int madvise_set_anon_name(struct mm_struct *mm, unsigned long start, > + unsigned long len_in, const char *name); > +#else > +static inline int > +madvise_set_anon_name(struct mm_struct *mm, unsigned long start, > + unsigned long len_in, const char *name) { > + return 0; > +} > +#endif You want to make this depend on CONFIG_PROC_FS. [...] > +#ifdef CONFIG_MMU > + > +#define ANON_VMA_NAME_MAX_LEN 64 > + > +static int prctl_set_vma(unsigned long opt, unsigned long addr, > + unsigned long size, unsigned long arg) > +{ > + struct mm_struct *mm = current->mm; > + char *name, *pch; > + int error; > + > + switch (opt) { > + case PR_SET_VMA_ANON_NAME: > + name = strndup_user((const char __user *)arg, > + ANON_VMA_NAME_MAX_LEN); > + > + if (IS_ERR(name)) > + return PTR_ERR(name); unless I am missing something NULL name would lead to an error rather than a name clearing as advertised above. > + > + for (pch = name; *pch != '\0'; pch++) { > + if (!isprint(*pch)) { > + kfree(name); > + return -EINVAL; > + } > + } > + > + mmap_write_lock(mm); > + error = madvise_set_anon_name(mm, addr, size, name); > + mmap_write_unlock(mm); > + kfree(name); > + break; > + default: > + error = -EINVAL; > + } > + > + return error; -- Michal Hocko SUSE Labs