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[34.150.221.228]) by smtp.gmail.com with ESMTPSA id 3-20020a05620a070300b006ce9e880c6fsm10345986qkc.111.2022.11.16.11.56.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Nov 2022 11:56:27 -0800 (PST) From: "Joel Fernandes (Google)" To: linux-kernel@vger.kernel.org Cc: "Joel Fernandes (Google)" , rostedt@goodmis.org, ribalda@google.com, zwisler@google.com, robdclark@gmail.com, Eric Biederman , kexec@lists.infradead.org Subject: [PATCH RFC] kexec: Freeze processes before kexec Date: Wed, 16 Nov 2022 19:56:24 +0000 Message-Id: <20221116195624.124092-1-joel@joelfernandes.org> X-Mailer: git-send-email 2.38.1.584.g0f3c55d4c2-goog MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" During kexec, it is possible for userspace to race with device_shutdown() causing accesses to GPU after pm_runtime suspend has already happened. Fix by freezing userspace before device_shutdown(). Such freezing is already being done if kernel supports KEXEC_JUMP and kexec_image->preserve_context is true. However, doing it if either of these are not true prevents crashes/races. This fixes the following crash during kexec reboot on an ARM64 device with adreno GPU: [ 292.534314] Kernel panic - not syncing: Asynchronous SError Interrupt [ 292.534323] Hardware name: Google Lazor (rev3 - 8) with LTE (DT) [ 292.534326] Call trace: [ 292.534328] dump_backtrace+0x0/0x1d4 [ 292.534337] show_stack+0x20/0x2c [ 292.534342] dump_stack_lvl+0x60/0x78 [ 292.534347] dump_stack+0x18/0x38 [ 292.534352] panic+0x148/0x3b0 [ 292.534357] nmi_panic+0x80/0x94 [ 292.534364] arm64_serror_panic+0x70/0x7c [ 292.534369] do_serror+0x0/0x7c [ 292.534372] do_serror+0x54/0x7c [ 292.534377] el1h_64_error_handler+0x34/0x4c [ 292.534381] el1h_64_error+0x7c/0x80 [ 292.534386] el1_interrupt+0x20/0x58 [ 292.534389] el1h_64_irq_handler+0x18/0x24 [ 292.534395] el1h_64_irq+0x7c/0x80 [ 292.534399] local_daif_inherit+0x10/0x18 [ 292.534405] el1h_64_sync_handler+0x48/0xb4 [ 292.534410] el1h_64_sync+0x7c/0x80 [ 292.534414] a6xx_gmu_set_oob+0xbc/0x1fc [ 292.534422] a6xx_get_timestamp+0x40/0xb4 [ 292.534426] adreno_get_param+0x12c/0x1e0 [ 292.534433] msm_ioctl_get_param+0x64/0x70 [ 292.534440] drm_ioctl_kernel+0xe8/0x158 [ 292.534448] drm_ioctl+0x208/0x320 [ 292.534453] __arm64_sys_ioctl+0x98/0xd0 [ 292.534461] invoke_syscall+0x4c/0x118 [ 292.534467] el0_svc_common+0x98/0x104 [ 292.534473] do_el0_svc+0x30/0x80 [ 292.534478] el0_svc+0x20/0x50 [ 292.534481] el0t_64_sync_handler+0x78/0x108 [ 292.534485] el0t_64_sync+0x1a4/0x1a8 [ 292.534632] Kernel Offset: 0x1a5f800000 from 0xffffffc008000000 [ 292.534635] PHYS_OFFSET: 0x80000000 [ 292.534638] CPU features: 0x40018541,a3300e42 [ 292.534644] Memory Limit: none Cc: rostedt@goodmis.org Cc: ribalda@google.com Cc: zwisler@google.com Cc: robdclark@gmail.com Signed-off-by: Joel Fernandes (Google) --- kernel/kexec_core.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index ca2743f9c634..2614a7f1f8a6 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -1175,6 +1175,12 @@ int kernel_kexec(void) } else #endif { + error =3D freeze_processes(); + if (error) { + error =3D -EBUSY; + goto Unlock; + } + kexec_in_progress =3D true; kernel_restart_prepare("kexec reboot"); migrate_to_reboot_cpu(); --=20 2.38.1.584.g0f3c55d4c2-goog