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(unknown [IPv6:2a01:e0a:5e3:6100:826d:bc07:e98c:84a]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: loicmolinari) by bali.collaboradmins.com (Postfix) with ESMTPSA id 12A4717E1154; Fri, 5 Dec 2025 10:12:22 +0100 (CET) From: =?UTF-8?q?Lo=C3=AFc=20Molinari?= To: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , Boris Brezillon , Rob Herring , Steven Price , Liviu Dudau , Melissa Wen , =?UTF-8?q?Ma=C3=ADra=20Canal?= , Hugh Dickins , Baolin Wang , Andrew Morton , =?UTF-8?q?Lo=C3=AFc=20Molinari?= , Al Viro , =?UTF-8?q?Miko=C5=82aj=20Wasiak?= , Christian Brauner , Nitin Gote , Andi Shyti , Jonathan Corbet , Christopher Healy , Matthew Wilcox , Bagas Sanjaya Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, kernel@collabora.com Subject: [PATCH v12 01/10] drm/shmem-helper: Simplify page offset calculation in fault handler Date: Fri, 5 Dec 2025 10:12:07 +0100 Message-ID: <20251205091216.150968-2-loic.molinari@collabora.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20251205091216.150968-1-loic.molinari@collabora.com> References: <20251205091216.150968-1-loic.molinari@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: DF19C1A000F X-Rspamd-Server: rspam02 X-Stat-Signature: ankg4g78dy87fz44co5or3mk3bb8wqj4 X-Rspam-User: X-HE-Tag: 1764925944-578427 X-HE-Meta: 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 Lte1n24G X63KruEFyj4Up8f7ru7TJcn6si5Fdlc23ax8drhKbTqH4S9bAioFyGgT4Hrll7Psk90NvnBK2y5+8vs4= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: For a fault at address addr, the page offset is page_offset = (vmf->address - vma->vm_start) >> PAGE_SHIFT = ((addr & PAGE_MASK) - vma->vm_start) >> PAGE_SHIFT = (addr - vma->vm_start) >> PAGE_SHIFT Since the faulty logical page offset based on VMA is vmf->pgoff = vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) We can slightly simplify the calculation using page_offset = vmf->pgoff - vma->vm_pgoff v11: - remove misleading comment - add Boris R-b Signed-off-by: Loïc Molinari Reviewed-by: Boris Brezillon --- drivers/gpu/drm/drm_gem_shmem_helper.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index dc94a27710e5..e47ab3ebb5c2 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -577,8 +577,8 @@ static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf) struct page *page; pgoff_t page_offset; - /* We don't use vmf->pgoff since that has the fake offset */ - page_offset = (vmf->address - vma->vm_start) >> PAGE_SHIFT; + /* Offset to faulty address in the VMA. */ + page_offset = vmf->pgoff - vma->vm_pgoff; dma_resv_lock(shmem->base.resv, NULL); -- 2.47.3