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Wed, 05 Mar 2025 18:09:01 +0100 Message-ID: <851bef96-245b-4f5c-8390-ab94dbc04063@web.de> Date: Wed, 5 Mar 2025 18:08:57 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird To: Ryosuke Yasuoka , dri-devel@lists.freedesktop.org, linux-mm@kvack.org, virtualization@lists.linux.dev, Andrew Morton , Chia-I Wu , Christoph Hellwig , Dmitry Osipenko , David Airlie , Gerd Hoffmann , Gurchetan Singh , Jocelyn Falempe , Maarten Lankhorst , Maxime Ripard , Simona Vetter , Thomas Zimmermann , Uladzislau Rezki Cc: LKML References: <20250305152555.318159-2-ryasuoka@redhat.com> Subject: Re: [PATCH drm-next 1/2] vmalloc: Add atomic_vmap Content-Language: en-GB From: Markus Elfring In-Reply-To: <20250305152555.318159-2-ryasuoka@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Provags-ID: V03:K1:vEp7fO8OsXvltY+7oiG0U4Qokb3J1idWk083MmpQMlGUeIwHTKL jRh7hs+24rFyD+jl09lH+ncvGeCwbtWg961JToNhl4VKePRb7+aYCgPFENm1vRX8pbHDA4i zxnOW+aDPcsXlw3NruQ/sLB2XxT7g5LpG8UHpGYjNpIoMcPvKStEF6y8FzzgWuO0EICoJKb vXAbMLOSUS+c/O6ilBHGw== X-Spam-Flag: NO UI-OutboundReport: notjunk:1;M01:P0:YxuzAM20H38=;gHkRljwq/KV5WGk1op49fkFicqc 9+hDF7PwhqCqW2f4kk5i/KcpduA11TJaBjXWyLI4L3VpqOzUiHb0XPmfXJCVmm7I+3fQmHoP9 DDnopOS6pVWYYhLTpJOL9Y/GMavuuRRvCio5xTqQLKw+WzCFxa2r2kgj4ptckTwDu8I5dOokT BjkuEjAB8Stv2pLpATxO64dtcZSQ0LIZdpevZXtonOkZKTdMp3QemYaudoA+dD92uRF7h2Hs1 ijSZhc9apGr3TirahGb3XO1jnLgb9HIz3I/L1Q8T82JLKCb94hBs5a34lVWmuG6IC45ajiS/W QXsIn2Qn1IkIDTik6ZpLzMq7wBIrMUeYuhx7GIPbe9nRuLzWGPzgbtw9UcuBXCiyAb7LHYSYo /JsqOTvvJ9uCVvcjBK45KWxXqfz+fg2wa+OM48FfL3bd9O3N37+BgtGONVz87jkoH8ZVDx3P8 /EUJo4g4x8buFuGXnIq+dO5lNNRzfgs3l7QZnAt9PjlEPIP5LffA0kj+TqYLhge1Nl6qhyA6V NXHOjPYArqM1zOkmjLmj2GfLwvxhpbrWEBlVFcetLW737LEASU2EBCKKLkTkncL7kCWbCHBeC rf5TQD0sE+J2Faqq4hU0u6XBP4q4Uxaeyo3hLULVzFLHvJQQSU/f+iN2RLowoTxYk5q4V2qBV xt10vUJahfgn3zh3C1ZCxPydJt5vPVOsqEAHOJ2tJ9h8KLgBzvhTnJUYpXDmi5QYfLxDu7eNb 67xd0Qii2mwZxGLJ2QLdAMH/8ep0o28WvNEchYkqgEUFf7Vy18Yxg3b7dkpazHS/+vlJNR1fx C//4EctTNRkqW5SJohwa6tSR6r2yZe+BmPzR1glbxoxiXLVI6emBXs+66x8/XVCFgKqzttxZe dDpP1CV7fKQEF2UNNrzPTjCECsPQImiQNBjW4vmeioM2/Il3M+lC2MiBB7GTRTx2+DaQq/dDZ jhx/N3t9ITztPm2Mbi1diyRRd8iRt+CaSkPbH6AwJUjH/eCVlZwNy/cqT7vgMkOa4Ys5JpIp3 A5bFO+O1DKofWhyf7vhJ+QcJ9SbHZqwQ2fiYB8HS5KirYR3kN8hXSelgRQcYDr7nHafgc8dsn D/NOp/0wwL5OnO9FuABzFnHWIZr5UMkRDVJJPL9qDYD8fs1BhL5gI640Lv+PiEk8iczDhgRBM JsHuPXZ5dmII8/gulPYM9EDdJdGOkE8zoPNZljZ4n8PtOJ3P0WYlApOLCFbZzbhCeL66vNxLy bQ2gWuCZfKwyWhCNEtUmUtBY3m9dcwIDB4OBhbxh5q0/C+Njt/cq7dYONtJJFNZqVaOvnZxlL n/Hem3o5coHPuAH0UUSCz+WpXNpOoyCm+WpnzYJYplznBNhMSZDWMoWOINx2w+l+7sevpSShH MoyxcTY+fRffbMemiXvtoU0Ny+AcsrQ0SrYWJjm6E3cA7xr2+qAXLbJn8rmENw87JXrsIOgTc 3hNdO/NPSGU+8NUDlEtV1UdHFCro= > Some drivers can use vmap in drm_panic, however, vmap is sleepable and > takes locks. Since drm_panic will vmap in panic handler, atomic_vmap > requests pages with GFP_ATOMIC and maps KVA without locks and sleep. See also: https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.14-rc5#n94 Regards, Markus