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[70.31.26.132]) by smtp.gmail.com with ESMTPSA id q12-20020a05620a2a4c00b006fef61300fesm1060738qkp.16.2022.12.22.13.47.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Dec 2022 13:47:24 -0800 (PST) Date: Thu, 22 Dec 2022 16:47:21 -0500 From: Peter Xu To: James Houghton Cc: Mike Kravetz , Muchun Song , David Hildenbrand , David Rientjes , Axel Rasmussen , Mina Almasry , Zach O'Keefe , Manish Mishra , Naoya Horiguchi , "Dr . David Alan Gilbert" , "Matthew Wilcox (Oracle)" , Vlastimil Babka , Baolin Wang , Miaohe Lin , Yang Shi , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v2 35/47] userfaultfd: require UFFD_FEATURE_EXACT_ADDRESS when using HugeTLB HGM Message-ID: References: <20221021163703.3218176-1-jthoughton@google.com> <20221021163703.3218176-36-jthoughton@google.com> MIME-Version: 1.0 In-Reply-To: <20221021163703.3218176-36-jthoughton@google.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 19FB31A0007 X-Stat-Signature: 3orxcbz8ikmmoft8c7pkfkgmxrofhst5 X-HE-Tag: 1671745647-111447 X-HE-Meta: U2FsdGVkX18ZPJ1dkLwWheYkhgmT6SYdvQszgfQjphWS1ftRJSjFa6imdcyb4Taz4/hpGbofsQSYbGWzfjEo4NN7G4uoJpcmXewwsod+Fiu3mcDRVA+c/6Bm/x8L6b56Q1SobWUdr5OMXCGMMQ55i0w7GMnzV/SHchqoTCITYtOeLgtPdYpC8GQwXOE2boowIlyInfPOs0oTDCnttKpHu7N4peMixF69H1Twxu0wDjOJ1IacyaG4FXEjGOoIp5fRErCo2s8iYQJJDHSKZl089dijoZvqPFiHbQzuHDqA9VkXkAdMpYE49ya76MIvgdjd6U7nDSF7S1cJhCn0uYznDD5COqqXOPlE9RNUaclI5t6q+5DYVI4WCr1ym6ymSWhDeQ5YiI//ox90BKjivz3kbyuHXCYKtFMJk7OmbNjB6BZ+a9OJXXC/U3CNqYkaUkwzCY92wvxs6UJgVx75D2TdDK31uP1pvvHZnDDlnq78zmr5l/4SJX0I6lJYJRqwBEg4ONzoYOGZS53H2btPMMV3fTN5lm7Mj/Vd7P/a/aD2g5ZGK7akrXs3KoC3yuanxrSCRzuIPfnnTgslO64Zok6QkNHP7ZMEGFXFyDPl17rPhYBBAOfjPRc2+1PocTcT+CB0fQ4hqJBlrN5BXBLeG2cFoQNozNEs/b3j+eilQayStYfgTR3uwYCVVX67Zt8pfpgfMZZs1GV27b64ItObrL0lU2p/U+xs0i7Iq2kYV7BAsr3HvJEB26YFQOtwzZ2d77OEV8uTu2VOoQx2W3/ClES7VO03mTM7wM/oFtV5ZRn1RQcP/dQTW4tzh6e2Vl4TOCnZ1Y9qCw4WIDYV+5lXu5f0hYh/95IPmnJz8whB+lGr5P4/Fx1YxtQhw/370bl9jqC/y6pBJH5paf193ugPMknN9wvXRrD5uXZ5PUaoEZjL4nrKvOzJeP/EGuxQbesBlX12/n/yF94r7OJkjpkp5+1 n6E6Dv+D 6AorSAGwE94Le+PlFVC8FO5QJjxasnJLu7PeM6CBGijW40cWz7drZyxhc7WjmNcOGoqrei4GaABbLMdyEGGU6vADSH9uFOpkL50mJXc+Db9ENFf5JOyJoGD9/n/s1ceNQWEt+/Xogl8Cla8s0mAEVZMucww== 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, Oct 21, 2022 at 04:36:51PM +0000, James Houghton wrote: > @@ -1990,6 +1990,17 @@ static int userfaultfd_api(struct userfaultfd_ctx *ctx, > ~(UFFD_FEATURE_MINOR_HUGETLBFS | UFFD_FEATURE_MINOR_SHMEM); > #ifndef CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING > uffdio_api.features &= ~UFFD_FEATURE_MINOR_HUGETLBFS_HGM; > +#else > + > + ret = -EINVAL; > + if ((uffdio_api.features & UFFD_FEATURE_MINOR_HUGETLBFS_HGM) && > + !(uffdio_api.features & UFFD_FEATURE_EXACT_ADDRESS)) This check needs to be done upon "features" or "ctx_features", rather than "uffdio_api.features". The latter is the one we'll report to the user only. > + /* > + * UFFD_FEATURE_MINOR_HUGETLBFS_HGM is mostly > + * useless without UFFD_FEATURE_EXACT_ADDRESS, > + * so require userspace to provide both. > + */ > + goto err_out; > #endif /* CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING */ > #endif /* CONFIG_HAVE_ARCH_USERFAULTFD_MINOR */ > > -- > 2.38.0.135.g90850a2211-goog > > -- Peter Xu