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b=oHKCbOs50OGhdryTHZVIrJJAH5cNWadJ96vBPL21JseHby43owQLI4TQNXRn8X6gJ TAnHb0VclvTH/ELo5PXr26ZhLJbSwD3gVlLvJn7Z0/7xX0d8g4qtgVFjgxpWwxbv1a 7r5CcrXGWEbeyhCP39VRFFsSay0aVbIrR1SurkK/zcKs46h1LZbloHKdjmJ9QcIWOB 93pv7I3n5DE5yAji0/HPOsX0hhylbUPeh4N5mBIdjWYLPd6EljlcjYkvh2JpbnVfqK 2Dhr9fLfrHgsT5U9G1HrOgWT69oD72z/B+kQJ6Kj2KlR/byBhBoVckK6V+QXJUFKRE 5uoKO6B92zc7w== Date: Sat, 11 Jul 2026 17:23:19 +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-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: ABAC6C000C X-Stat-Signature: ym7ttb7mxwhhu5m5t734drg4zxphbk8y X-HE-Tag: 1783787027-68977 X-HE-Meta: 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 naMi1SXk Wcq2SuHVhsl2UmmZYFCGAlVcasRnpzla4QBZDHvWm1tCKEJlD9uCYxA+37+kZEFqloK1N3MdPzG4CKavVb2ATf0YlqJK7OidWJbnBWD10HD2+Fmf5mQBpz5PMxy3qW3LAsMLvJC2OIYspO+8pEaBERbQa6nx53Zv7Qkk4+QaeWm+Z8CLgW0r+CAXVuQX1ZZ1LsFH8fYVKFjwsN10/fdO7gINvfY8yoUFhzijxWAn4fuxYGaWL1g/s1iAgVejEjFSkYtBbm4ByWGhyG1k8bD0PlbHWxh2l/ZudKON5O76gK7WiJiU= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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. For me it just feels like the most silly place to put that check, a VMA flags update should update VMA flags not start randomly asserting silly things :) > > > > > I want VMA flags to be a clean stateless thing, other than the flags > > themselves. Implicit, unrelated, asserts or lock acquisitions in general should > > be done separately IMO. > > > > Anyway, > > Reviewed-by: Zi Yan Thanks! > > -- > Best Regards, > Yan, Zi > Cheers, Lorenzo