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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 D136017E1154; Fri, 5 Dec 2025 10:12:06 +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 v11 01/10] drm/shmem-helper: Simplify page offset calculation in fault handler Date: Fri, 5 Dec 2025 10:11:54 +0100 Message-ID: <20251205091203.150895-2-loic.molinari@collabora.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20251205091203.150895-1-loic.molinari@collabora.com> References: <20251205091203.150895-1-loic.molinari@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 99F991C0016 X-Stat-Signature: s5kecc5uzgfc4z6snrjkyj6jcddzrrrq X-Rspam-User: X-HE-Tag: 1764925930-784565 X-HE-Meta: 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 x4NXGGXD 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 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