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a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783789480; bh=+Kwd9D5Wl2KO1Q3Bx8l5+fiMeXu2P1OtbVPUfZ/bfbo=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=k75eMTHbfY5dLiist6X1WccVv3k4otHBJCwIOTe46YBHnqrIF1xmytrUrRJODV0h2 NFmVNF/K5+hQkIVW3bv6RCnCkOSV5BteTL51MGqvOw9+FwfCEdTh0lJASD7uVwbR0D 7id+6F1QOheKs0/qV7VtYbBBrYuorsecGOcn4P+Aedutt57oKLfai/LPb47xTkHe2v Vxu5p2eAfg3qWGWcIPsPlaAGCDayA6g0QKSaIAbXO2OSh1LdCes8X+y9FM6C+1Eu7H /PK8nbJzJ0+/7/dPZ2uAj/ztBJv5OD5W3R7oCXqO8Y2s8cuPNpie8Ma1uT2vWb6Thl oZYPNvSdCQdnQ== Date: Sat, 11 Jul 2026 18:04:14 +0100 From: Lorenzo Stoakes To: Zi Yan Subject: Re: [PATCH 12/13] mm/mprotect: convert mprotect code to use vma_flags_t Message-ID: References: <7ef626d8a12dc742cfc09d080be5dc09850e873a.1782760670.git.ljs@kernel.org> <20260701160917.91435-1-lance.yang@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Message-ID-Hash: 24JJYECQQPIWAJ4O7S7I44VB4KWWSPDO X-Message-ID-Hash: 24JJYECQQPIWAJ4O7S7I44VB4KWWSPDO X-MailFrom: ljs@kernel.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: Lance Yang , akpm@linux-foundation.org, tsbogend@alpha.franken.de, maddy@linux.ibm.com, mpe@ellerman.id.au, maarten.lankhorst@linux.intel.com, mripard@kernel.org, simona@ffwll.ch, l.stach@pengutronix.de, inki.dae@samsung.com, sw0312.kim@samsung.com, kyungmin.park@samsung.com, krzk@kernel.org, peter.griffin@linaro.org, jani.nikula@linux.intel.com, joonas.lahtinen@linux.intel.com, rodrigo.vivi@intel.com, tursulin@ursulin.net, robin.clark@oss.qualcomm.com, lumag@kernel.org, dakr@kernel.org, tomi.valkeinen@ideasonboard.com, hjc@rock-chips.com, heiko@sntech.de, andy.yan@rock-chips.com, thierry.reding@kernel.org, mperttunen@nvidia.com, kraxel@redhat.com, dmitry.osipenko@collabora.com, zack.rusin@broadcom.com, matthew.brost@intel.com, thomas.hellstrom@linux.intel.com, oleksandr_andrushchenko@epam.com, deller@gmx.de, bcrl@kvack.org, viro@zeniv.linux.org.uk, brauner@kernel.org, muchun.song@linux.dev, osalvador@suse.de, david@kernel.org, baolin.wang@linux.alibaba.com, liam@infradead.org, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, hughd@google.com, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, jannh@google.com, pfalcato@suse.de, kees@kernel.org, perex@perex.cz, tiwai@suse.com, linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, dri-devel@lists.freedesktop.org, etnaviv@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, intel-gfx@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org, nouveau@lists.freedesktop.org, linux-rockchip@lists.infradead.org, linux-tegra@vger.kernel.org, virtualization@lists.linux.dev, intel-xe@lists.freedesktop.org, xen-devel@lists.xenproject.org, linux-fbdev@vger.kernel.org, linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-sound@vger.kernel.org X-Mailman-Version: 3.3.8 Precedence: list List-Id: Nouveau development list Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On Wed, Jul 08, 2026 at 10:16:15PM -0400, Zi Yan wrote: > On Thu Jul 2, 2026 at 11:53 AM EDT, Lorenzo Stoakes wrote: > > On Thu, Jul 02, 2026 at 12:09:17AM +0800, Lance Yang wrote: > >> > >> On Mon, Jun 29, 2026 at 08:25:35PM +0100, Lorenzo Stoakes wrote: > >> >Replace use of the legacy vm_flags_t flags with vma_flags_t values > >> >throughout the mprotect logic. > >> > > >> >Note that we retain the legacy vm_flags_t bit shifting code in > >> >do_mprotect_key(), deferring a vma_flags_t approach to this for the time > >> >being. > >> > > >> >Additionally update comments to reflect the changes to be consistent. > >> > > >> >No functional change intended. > >> > > >> >Signed-off-by: Lorenzo Stoakes > >> >--- > >> > mm/mprotect.c | 16 ++++++++-------- > >> > 1 file changed, 8 insertions(+), 8 deletions(-) > >> > > >> >diff --git a/mm/mprotect.c b/mm/mprotect.c > >> >index 9cbf932b028c..c9504b2a2525 100644 > >> >--- a/mm/mprotect.c > >> >+++ b/mm/mprotect.c > >> >@@ -40,7 +40,7 @@ > >> > > >> > static bool maybe_change_pte_writable(struct vm_area_struct *vma, pte_t pte) > >> > { > >> >- if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE))) > >> >+ if (WARN_ON_ONCE(!vma_test(vma, VMA_WRITE_BIT))) > >> > return false; > >> > > >> > /* Don't touch entries that are not even readable. */ > >> >@@ -97,7 +97,7 @@ static bool can_change_shared_pte_writable(struct vm_area_struct *vma, > >> > bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr, > >> > pte_t pte) > >> > { > >> >- if (!(vma->vm_flags & VM_SHARED)) > >> >+ if (!vma_test(vma, VMA_SHARED_BIT)) > >> > return can_change_private_pte_writable(vma, addr, pte); > >> > > >> > return can_change_shared_pte_writable(vma, pte); > >> >@@ -194,7 +194,7 @@ static __always_inline void set_write_prot_commit_flush_ptes(struct vm_area_stru > >> > { > >> > bool set_write; > >> > > >> >- if (vma->vm_flags & VM_SHARED) { > >> >+ if (vma_test(vma, VMA_SHARED_BIT)) { > >> > set_write = can_change_shared_pte_writable(vma, ptent); > >> > prot_commit_flush_ptes(vma, addr, ptep, oldpte, ptent, nr_ptes, > >> > /* idx = */ 0, set_write, tlb); > >> >@@ -811,8 +811,8 @@ mprotect_fixup(struct vma_iterator *vmi, struct mmu_gather *tlb, > >> > vm_unacct_memory(nrpages); > >> > > >> > /* > >> >- * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major > >> >- * fault on access. > >> >+ * Private VMA_LOCKED_BIT VMA becoming writable: trigger COW to avoid > >> >+ * major fault on access. > >> > */ > >> > if (vma_flags_test(&new_vma_flags, VMA_WRITE_BIT) && > >> > vma_flags_test(&old_vma_flags, VMA_LOCKED_BIT) && > >> >@@ -886,7 +886,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len, > >> > goto out; > >> > start = vma->vm_start; > >> > error = -EINVAL; > >> >- if (!(vma->vm_flags & VM_GROWSDOWN)) > >> >+ if (!vma_test(vma, VMA_GROWSDOWN_BIT)) > >> > goto out; > >> > } else { > >> > if (vma->vm_start > start) > >> >@@ -894,7 +894,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len, > >> > if (unlikely(grows & PROT_GROWSUP)) { > >> > end = vma->vm_end; > >> > error = -EINVAL; > >> >- if (!(vma->vm_flags & VM_GROWSUP)) > >> >+ if (!vma_test(vma, VMA_GROWSUP_BIT)) > >> > >> IIUC, should this be > >> > >> if (!vma_test_single_mask(vma, VMA_GROWSUP)) > >> > >> instead? > >> > >> #elif defined(CONFIG_PARISC) > >> #define VM_GROWSUP INIT_VM_FLAG(GROWSUP) > >> ... > >> #ifndef VM_GROWSUP > >> #define VM_GROWSUP VM_NONE > >> ... > >> > >> VM_GROWSUP is only defined as GROWSUP on parisc and becomes VM_NONE > >> elsewhere. But VMA_GROWSUP_BIT is the raw ARCH_1 bit, which is also used > >> for other arch-specific VMA flags: > >> > >> DECLARE_VMA_BIT_ALIAS(SAO, ARCH_1), /* Strong Access Ordering (powerpc) */ > >> DECLARE_VMA_BIT_ALIAS(GROWSUP, ARCH_1), /* parisc */ > >> DECLARE_VMA_BIT_ALIAS(SPARC_ADI, ARCH_1), /* sparc64 */ > >> DECLARE_VMA_BIT_ALIAS(ARM64_BTI, ARCH_1), /* arm64 */ > >> DECLARE_VMA_BIT_ALIAS(ARCH_CLEAR, ARCH_1), /* sparc64, arm64 */ > >> DECLARE_VMA_BIT_ALIAS(MAPPED_COPY, ARCH_1), /* !CONFIG_MMU */ > >> > >> Other vma_test() changes look fine to me: just fixed INIT_VM_FLAG() > >> masks matching their VMA_*_BIT :) > > > > Thanks you're right, will fix! > > > > Again I swear I ran claude on all of this so it's failing me here :) > > > > Is it better to add something like below to avoid misuse these mutually > exclusive bit aliases? > > An example for VMA_GROWSUP_BIT: > > #if defined(CONFIG_PARISC) > DECLARE_VMA_BIT_ALIAS(GROWSUP, ARCH_1), /* parisc */ > #else > /* make VMA_GROWSUP_BIT a build bug on */ > #endif Nah we can't... > > Hmm, these VMA_*_BIT are enum items, so the above might not be possible. ...because of this but also this is the canonical definition and we want to use it for the VMA_xxx form. > An alternative is to only define them for the corresponding config and > you will get build errors when trying to use them directly and the > config is not enabled. Otherwise, misuses like "vma_test(vma, > VMA_GROWSUP_BIT)" is harder to uncover. Yeah good idea, I may add a new DECLARE_INTERNAL_VMA_BIT() that gives you __VMA_xxx_BIT, so nobody makes the obvious mistake and we force uses of safe VMA_xxx form. Hmm :) > > > -- > Best Regards, > Yan, Zi > Thanks, Lorenzo