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b=UQeTQQM7/zogPNVpPumivekv/Dm65tJwKSGkKyUaN15OK2ePQoOxgmoczQXNeufyu mPB2SeO/+jaR+zlJiyLVdyWAwHg7D0CKx8xMhyA5MDEdHDSR6TPUNUJn+Nzb/es+VO 1AGLLXVLTi7PuZQkYtNin4NBM5SzIQlt5sWd9Tt0MOCtyaJ26niLtZLm/iWL4WgjoE nytqWs/CMB6G26FmrITyykLrDBQPn0ehby972yRXsbQJ2wOYF8M/bvBoXBfucUYQHe 8/x2mtOwd5qD3Tv70Taj9RQTidlVV5lxGicVGK4dGGf0RiLlLhHP5bQmNpx1vNrQvn rYrD/ste49T1Q== Date: Sat, 11 Jul 2026 17:44:53 +0100 From: Lorenzo Stoakes To: Zi Yan 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, 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, 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 Subject: Re: [PATCH 10/13] mm/vma: convert miscellaneous uses of VMA flags in core mm Message-ID: References: <1e7d834c887b6a65627d730addcff13d458c6268.1782760670.git.ljs@kernel.org> <20260702131233.59026-1-lance.yang@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: BB38B18000A X-Stat-Signature: icpzeg9dht5bykwwj943ewwupr7cxx94 X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1783788321-539064 X-HE-Meta: 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 +cj95ZLB FzH2UIN8NNLJ6cOEujdOEHi4jHfCMTcTgwWGd+e6EX1KzIiAykPjV49UBk7RrEABDxbpZ9wdqoZRoA7UFjDF0V8SE2y8N509LNCN88+SAxi9DXZBeSkwYUtkIN6kUn+yxNANWGfkFuOySnv47wRBo5GvIMc5QkPoCk3uk/2p/0lXBDe0mySDCvtdWiswV5Zjv3bEW+vYG7aHoO1+4bK6bumqTugMpSl3YHhdTMKIERQDDig4T8ed6L0mYRgfJbHq0umV//04dNf090j/XyoIG9rLysw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, Jul 11, 2026 at 05:23:39PM +0100, Lorenzo Stoakes wrote: > On Wed, Jul 08, 2026 at 09:52:19PM -0400, Zi Yan wrote: > > On Thu Jul 2, 2026 at 11:46 AM EDT, Lorenzo Stoakes wrote: > > > On Thu, Jul 02, 2026 at 09:12:33PM +0800, Lance Yang wrote: > > >> > > >> On Mon, Jun 29, 2026 at 08:25:33PM +0100, Lorenzo Stoakes wrote: > > >> >Update various uses of legacy flags in vma.c and mmap.c to the new > > >> >vma_flags_t type, updating comments alongside them to be consistent. > > >> > > > >> >Also update __install_special_mapping() to rearrange things slightly to > > >> >accommodate the changes. > > >> > > > >> >Signed-off-by: Lorenzo Stoakes > > >> >--- > > >> [...] > > >> >diff --git a/mm/vma.c b/mm/vma.c > > >> >index b81c05e67a61..ab2ef0f04420 100644 > > >> >--- a/mm/vma.c > > >> >+++ b/mm/vma.c > > >> >@@ -3417,23 +3417,27 @@ struct vm_area_struct *__install_special_mapping( > > >> > vm_flags_t vm_flags, void *priv, > > >> > const struct vm_operations_struct *ops) > > >> > { > > >> >- int ret; > > >> >+ vma_flags_t vma_flags = legacy_to_vma_flags(vm_flags); > > >> > struct vm_area_struct *vma; > > >> >+ int ret; > > >> > > > >> > vma = vm_area_alloc(mm); > > >> >- if (unlikely(vma == NULL)) > > >> >+ if (unlikely(!vma)) > > >> > return ERR_PTR(-ENOMEM); > > >> > > > >> >- vma_set_range(vma, addr, addr + len, 0); > > >> >- vm_flags |= vma_flags_to_legacy(mm->def_vma_flags) | VM_DONTEXPAND; > > >> >+ vma_flags_set_mask(&vma_flags, mm->def_vma_flags); > > >> >+ vma_flags_set(&vma_flags, VMA_DONTEXPAND_BIT); > > >> > if (pgtable_supports_soft_dirty()) > > >> >- vm_flags |= VM_SOFTDIRTY; > > >> >- vm_flags_init(vma, vm_flags & ~VM_LOCKED_MASK); > > >> >+ vma_flags_set(&vma_flags, VMA_SOFTDIRTY_BIT); > > >> >+ vma_flags_clear_mask(&vma_flags, VMA_LOCKED_MASK); > > >> >+ vma->flags = vma_flags; > > >> > > >> Maybe worth a vma_flags_init() helper here to mirror vm_flags_init()? > > >> With this open-coded, we lose the soft-dirty WARN_ON_ONCE sanity check. > > >> > > >> Might be nicer to keep that check in one place ;) > > > > > > I really hate all the VMA flag accessors, they conflate things horribly - we > > > should be explicitly taking VMA write locks when we need to (and often killable > > > ones actually) not assuming that a VMA flags accessor does (they should at most > > > assert). > > > > > > This case is even more terribly egregious - you are setting flags at an > > > arbitrary time, why are we asserting something about softdirty? > > > > > > You may update them as part of initialisation, maybe not. It's far from a > > > guarantee and feels like a lazy place to put it. > > > > > > BUT obviously it's an oversight not to open code that here, so I'll update the > > > patch to do that! > > > > What do you want to open code here? softdirty WARN_ON_ONCE()? > > As you can tell I said this reflexively without checking the code :) > > > > > vma_flags gets VMA_SOFTDIRTY_BIT just above vma->flags, why do we need a > > check after that? > > And yeah it's completely unnecessary, indeed. > > > > > BTW, if you think the check is needed, patch 9 will need to be updated, > > since the same pattern appears in create_init_stack_vma(). > > I'll check to see if it's valid there. Exactly the same case as here, unnecessary :) Cheers, LOrenzo