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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 13DFC17E1157; Tue, 2 Dec 2025 11:17:24 +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: Tue, 2 Dec 2025 11:17:11 +0100 Message-ID: <20251202101720.3129-2-loic.molinari@collabora.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20251202101720.3129-1-loic.molinari@collabora.com> References: <20251202101720.3129-1-loic.molinari@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 82BA9C000E X-Stat-Signature: is9bep6ei4w6zt59z13en75nhu99cfxs X-HE-Tag: 1764670647-556947 X-HE-Meta: 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 Wv1hxw/d EqTS8xArhgnL+WafGRIR0cBpUP83nkX2uaKT/NX2wHybDgwKA4qgnRcAJgBrE6XlGNlKgUP+GVaOyld1FU7jS0AKXOq6o2PhJAH0ykQw4W8jJvy1Mok3TrTRPSCVPIIGk79ru6NN+ep47TPG3hMn8aoEPSq7ab7kXgsioc0gLnanuXZD04vLCM2hQMDvIVTKQxMS2wJIeduUTrXLhsD1wBFsdWrGMIqq8M5iVKZ7310KRBfIGeS2fsSfBNe5Z1xvsWNkNJ5WUN+krzp1PYUBJpN10oGu/rHuyz+MfE9tYsCBCj4H8O+nAk0Cf+xHcPt7u19CJUWD3p6cdOWHKfY9FpYxL3Ip0eCsWEtWSQbfy/FsOCUNh/N6rp/uyq8bPL6F0VgCq 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