From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-170.mta0.migadu.com (out-170.mta0.migadu.com [91.218.175.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 083693EDE6E for ; Thu, 2 Jul 2026 11:16:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.170 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782990968; cv=none; b=jFZxWGQJ13BSjMuIaufC+AAz8lWl0J1zY/9a/+j6eCQ2GaF43hzZ2993xZJaLlolonZkyEqSerbiBR5TO5WWhzxzwDVqeTZ2b2pgeKM7BHWdYBDlQ9WzR27rB4vUa9i/TW5mRpwfBUBwMnv0t6cIxbemZmXE5EKm0dDWr6EoxJQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782990968; c=relaxed/simple; bh=GnYBDGATmtulOrbHYieuBQYJQv+WuoHKcBOPpP2DOUE=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=NAJMy5AGgeS+lBlCtKprbeaJ7L437Mj06WI1bo0YWoil8HjomL0Y5p0FWGS6uFpsJjb6sMGS2TVln1bzhJLo0riZfJS9D3icVsH1Whx4nAk18Z2FPTnhysbakXBen0bQcGcDX4tS6iNbsi67qR9oFlYaN5QbrE6pNRaycwd/gtE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=SNO+TI3y; arc=none smtp.client-ip=91.218.175.170 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="SNO+TI3y" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1782990951; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=MXoiAeiZxppUV0bbr36tbNoILtIVkAZHXOhXlmlq9aE=; b=SNO+TI3ysBG4+DhR3hPTF1SvhO32c4IR52yjAPmkR78MakGGmD/cQOYIcE8MmMX2BXfJ/B PngJwUk8MPDHueMWfaVQgxbOjSa6VTjHZniUa88SClGCvA5JNzJYRen32CdMAokXiIgXtC 8TVZTPLK3UhpO1X2vjoT/Jd84+uq0gc= From: Lance Yang To: ljs@kernel.org Cc: akpm@linux-foundation.org, tsbogend@alpha.franken.de, maddy@linux.ibm.com, mpe@ellerman.id.au, maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@gmail.com, 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, lyude@redhat.com, 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, jonathanh@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, ziy@nvidia.com, baolin.wang@linux.alibaba.com, liam@infradead.org, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, 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 Subject: Re: [PATCH 02/13] mm/vma: update do_mmap() to use vma_flags_t Date: Thu, 2 Jul 2026 19:15:31 +0800 Message-Id: <20260702111531.64883-1-lance.yang@linux.dev> In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On Mon, Jun 29, 2026 at 08:25:25PM +0100, Lorenzo Stoakes wrote: >The core do_mmap() function accepts a vm_flags_t parameter which it then >manipulates before passing to mmap_region() to do the heavy lifting of the >memory mapping. > >Update do_mmap() to instead accept a vma_flags_t parameter, and adjust all >the logic within do_mmap() to manipulate this instead. > >This is as part of the ongoing effort to convert VMA flags from a system >word size to a bitmap type which allows us to unrestrict the number of VMA >flags, as well as gain control over how VMA flag manipulation occurs. > >We do not cascade these changes to all functions which accept vm_flags_t, >but rather use vma_flags_to_legacy() where necessary, specifically >deferring converting calc_vm_prot_bits(), calc_vm_flag_bits() and >__get_unmapped_area() to vma_flags_t. > >Also utilise the new vma_flags_can_grow() predicate which correctly handles >the case of architectures without upward growing stacks. > >As part of this change, introduce VMA_SHADOW_STACK so we can correctly >handle the case of the shadow stack not being defined. > >No functional change intended. > >Signed-off-by: Lorenzo Stoakes >--- Not exactly a small one :) I stared at this patch for a while, hopefully don't miss anythig ... Just one tiny nit below. Overall, LGTM, feel free to add: Reviewed-by: Lance Yang [...] >diff --git a/mm/mmap.c b/mm/mmap.c >index 46174e706bbe..547352183214 100644 >--- a/mm/mmap.c >+++ b/mm/mmap.c [...] >@@ -488,23 +496,27 @@ unsigned long do_mmap(struct file *file, unsigned long addr, > * Check to see if we are violating any seals and update VMA > * flags if necessary to avoid future seal violations. > */ >- err = memfd_check_seals_mmap(file, &vm_flags); >+ err = memfd_check_seals_mmap(file, &vma_flags); > if (err) > return (unsigned long)err; > } else { > switch (flags & MAP_TYPE) { > case MAP_SHARED: >- if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) >+ if (vma_flags_can_grow(&vma_flags)) > return -EINVAL; > /* > * Ignore pgoff. > */ > pgoff = 0; >- vm_flags |= VM_SHARED | VM_MAYSHARE; >+ vma_flags_set(&vma_flags, VMA_SHARED_BIT, VMA_MAYSHARE_BIT); > break; >- case MAP_DROPPABLE: >- if (VM_DROPPABLE == VM_NONE) >+ case MAP_DROPPABLE: { >+ vma_flags_t droppable = VMA_DROPPABLE; >+ >+ if (vma_flags_empty(&droppable)) > return -EOPNOTSUPP; >+ vma_flags_set_mask(&vma_flags, droppable); >+ > /* > * A locked or stack area makes no sense to be droppable. > * >@@ -515,23 +527,24 @@ unsigned long do_mmap(struct file *file, unsigned long addr, > */ > if (flags & (MAP_LOCKED | MAP_HUGETLB)) > return -EINVAL; >- if (vm_flags & (VM_GROWSDOWN | VM_GROWSUP)) >+ if (vma_flags_can_grow(&vma_flags)) > return -EINVAL; > >- vm_flags |= VM_DROPPABLE; Old code checked VM_GROWSDOWN|VM_GROWSUP before seting VM_DROPPABLE. New code flips that around. Hmm, shouldn't master, just made me look twice ;) Maybe keep old order? Cheers, Lance >- > /* > * If the pages can be dropped, then it doesn't make > * sense to reserve them. > */ >- vm_flags |= VM_NORESERVE; >+ vma_flags_set(&vma_flags, VMA_NORESERVE_BIT); > > /* > * Likewise, they're volatile enough that they > * shouldn't survive forks or coredumps. > */ >- vm_flags |= VM_WIPEONFORK | VM_DONTDUMP; >+ vma_flags_set(&vma_flags, VMA_WIPEONFORK_BIT, >+ VMA_DONTDUMP_BIT); >+ > fallthrough; >+ } > case MAP_PRIVATE: > /* > * Set pgoff according to addr for anon_vma. [...]