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Ehrhardt" Cc: dri-devel@lists.freedesktop.org, Steven Price , Liviu Dudau , Andrew Morton , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] drm/panthor: Check VMA boundaries for PMD mappings Message-ID: <20260624123313.3dcd8b8b@fedora-2.home> In-Reply-To: <20260624122636.22d34274@fedora-2.home> References: <20260623181942.1536598-1-lk@c--e.de> <20260624122636.22d34274@fedora-2.home> Organization: Collabora X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: C03471A0005 X-Stat-Signature: 9gcmqpdg4uwyqta3xnjp5x9zjo8ter8m X-HE-Tag: 1782297200-536536 X-HE-Meta: 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 cT26ijLW LV+mj6mVLVb92DSSB4Mbw73YPh5LiluspcqnOqj7PEW/QauLKnTzglKMVUWLc3gid2ngiTK8L1yuqczMYL8E1sCJqa2KQJ+WcshCa+6Uo/+p3wzkOrlhL59phxCx8PMnb4hpqYcJ/xeNggpHIS7M9/9fh9bGs9/DHzca7MZEwf06dq+zIAzqRCBXwrxhRxdZ/4bWeBBIXaBQrLjTpNed9JexIlKK4oR0sQcFgYvWG5QkSGn4LNfdVjMQesqfthFlGxOPABVHKC5NhoSEN1D5iH69fv6xlW940TVAho8smdN+Ogy0/fsUYIsD8S062mVOqVjZDR8PF1fsCzlu2qMlIZsfgTxmxUPxMMn/5SCt71BdYDijUxXwsQ4rvqEob9m6Lbj4F3PWneS1yUbANTUuIQ6gUPlzsCDlC1nFmcnRkT/AW44g8cUayhgVq0Rc6G1OEUuaA9mshqUhZLZo= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 24 Jun 2026 12:26:36 +0200 Boris Brezillon wrote: > On Tue, 23 Jun 2026 20:19:42 +0200 > "Christian A. Ehrhardt" wrote: > > > When checking a different patch[1] sashiko AI pointed out that > > panthor needs the same fix[2]: > > > > In the ->huge_fault handler do not install a PMD huge page > > mapping if the huge page exceeds the boundaries of the VMA. > > > > [1] https://lore.kernel.org/lkml/20260622215718.1532689-1-lk@c--e.de/ > > [2] https://sashiko.dev/#/patchset/20260622215718.1532689-1-lk%40c--e.de > > > > Cc: Boris Brezillon > > Cc: Steven Price > > Cc: Liviu Dudau > > Fixes: 68cbf96b1e9b ("drm/panthor: Part ways with drm_gem_shmem_object") > > Signed-off-by: Christian A. Ehrhardt > > I know the discussion is ongoing to decide what we should do about > these huge_fault() handlers, but I think it's worth getting this fix in > in the meantime. > > Reviewed-by: Boris Brezillon BTW, I saw shashiko complain about our page_offset calculation which should look something like page_offset = vmf->pgoff - drm_vma_node_start(&bo->base.vma_node); to be immune to the vma->vm_{start,pgoff} adjustments done when the VMA is split. > > > --- > > drivers/gpu/drm/panthor/panthor_gem.c | 6 +++++- > > 1 file changed, 5 insertions(+), 1 deletion(-) > > > > NOTE: > > The panthor version is only compile tested because I don't > > have the hardware. However, the code is identical to that > > fixed in [1] and I have a reproducer for that. > > > > No need for for stable backports. The code is new in 7.1. > > > > diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c > > index a1e2eb1ca7bb..54535bae2b0c 100644 > > --- a/drivers/gpu/drm/panthor/panthor_gem.c > > +++ b/drivers/gpu/drm/panthor/panthor_gem.c > > @@ -802,9 +802,13 @@ static vm_fault_t insert_page(struct vm_fault *vmf, unsigned int order, struct p > > } else if (order == PMD_ORDER) { > > unsigned long pfn = page_to_pfn(page); > > unsigned long paddr = pfn << PAGE_SHIFT; > > + struct vm_area_struct *vma = vmf->vma; > > + unsigned long start = ALIGN_DOWN(vmf->address, PMD_SIZE); > > + unsigned long end = start + PMD_SIZE; > > + bool in_range = vma->vm_start <= start && end <= vma->vm_end; > > bool aligned = (vmf->address & ~PMD_MASK) == (paddr & ~PMD_MASK); > > > > - if (aligned && > > + if (aligned && in_range && > > folio_test_pmd_mappable(page_folio(page))) { > > pfn &= PMD_MASK >> PAGE_SHIFT; > > return vmf_insert_pfn_pmd(vmf, pfn, vmf->flags & FAULT_FLAG_WRITE); >