# git rev-parse -q --verify a4d63c3732f1a0c91abcf5b7f32b4ef7dcd82025^{commit} a4d63c3732f1a0c91abcf5b7f32b4ef7dcd82025 already have revision, skipping fetch # git checkout -q -f -B kisskb a4d63c3732f1a0c91abcf5b7f32b4ef7dcd82025 # git clean -qxdf # < git log -1 # commit a4d63c3732f1a0c91abcf5b7f32b4ef7dcd82025 # Author: Jason A. Donenfeld # Date: Mon Sep 28 12:35:07 2020 +0200 # # mm: do not rely on mm == current->mm in __get_user_pages_locked # # It seems likely this block was pasted from internal_get_user_pages_fast, # which is not passed an mm struct and therefore uses current's. But # __get_user_pages_locked is passed an explicit mm, and current->mm is not # always valid. This was hit when being called from i915, which uses: # # pin_user_pages_remote-> # __get_user_pages_remote-> # __gup_longterm_locked-> # __get_user_pages_locked # # Before, this would lead to an OOPS: # # BUG: kernel NULL pointer dereference, address: 0000000000000064 # #PF: supervisor write access in kernel mode # #PF: error_code(0x0002) - not-present page # CPU: 10 PID: 1431 Comm: kworker/u33:1 Tainted: P S U O 5.9.0-rc7+ #140 # Hardware name: LENOVO 20QTCTO1WW/20QTCTO1WW, BIOS N2OET47W (1.34 ) 08/06/2020 # Workqueue: i915-userptr-acquire __i915_gem_userptr_get_pages_worker [i915] # RIP: 0010:__get_user_pages_remote+0xd7/0x310 # Call Trace: # __i915_gem_userptr_get_pages_worker+0xc8/0x260 [i915] # process_one_work+0x1ca/0x390 # worker_thread+0x48/0x3c0 # kthread+0x114/0x130 # ret_from_fork+0x1f/0x30 # CR2: 0000000000000064 # # This commit fixes the problem by using the mm pointer passed to the # function rather than the bogus one in current. # # Fixes: 008cfe4418b3 ("mm: Introduce mm_struct.has_pinned") # Tested-by: Chris Wilson # Reported-by: Harald Arnesen # Reviewed-by: Jason Gunthorpe # Reviewed-by: Peter Xu # Signed-off-by: Jason A. Donenfeld # Signed-off-by: Linus Torvalds # < /opt/cross/kisskb/korg/gcc-4.9.4-nolibc/mips-linux/bin/mips-linux-gcc --version # < /opt/cross/kisskb/korg/gcc-4.9.4-nolibc/mips-linux/bin/mips-linux-ld --version # < git log --format=%s --max-count=1 a4d63c3732f1a0c91abcf5b7f32b4ef7dcd82025 # < make -s -j 24 ARCH=mips O=/kisskb/build/linus_mips-defconfig_mips-gcc4.9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-4.9.4-nolibc/mips-linux/bin/mips-linux- defconfig # < make -s -j 24 ARCH=mips O=/kisskb/build/linus_mips-defconfig_mips-gcc4.9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-4.9.4-nolibc/mips-linux/bin/mips-linux- help # make -s -j 24 ARCH=mips O=/kisskb/build/linus_mips-defconfig_mips-gcc4.9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-4.9.4-nolibc/mips-linux/bin/mips-linux- olddefconfig # make -s -j 24 ARCH=mips O=/kisskb/build/linus_mips-defconfig_mips-gcc4.9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-4.9.4-nolibc/mips-linux/bin/mips-linux- FIT description: Linux 5.9.0-rc7-ga4d63c3732f1 Created: Tue Sep 29 05:19:40 2020 Image 0 (kernel@0) Description: Linux 5.9.0-rc7-ga4d63c3732f1 Created: Tue Sep 29 05:19:40 2020 Type: Kernel Image Compression: gzip compressed Data Size: 5086766 Bytes = 4967.54 KiB = 4.85 MiB Architecture: MIPS OS: Linux Load Address: 0x80100000 Entry Point: 0x809524d0 Hash algo: sha1 Hash value: 4aabb0d6da78843c937e767b09c163a9022da434 Image 1 (fdt@boston) Description: img,boston Device Tree Created: Tue Sep 29 05:19:40 2020 Type: Flat Device Tree Compression: uncompressed Data Size: 3793 Bytes = 3.70 KiB = 0.00 MiB Architecture: MIPS Hash algo: sha1 Hash value: 4799f50d688573234da6e9d7701234d394759ef4 Image 2 (fdt@ni169445) Description: NI 169445 device tree Created: Tue Sep 29 05:19:40 2020 Type: Flat Device Tree Compression: uncompressed Data Size: 1871 Bytes = 1.83 KiB = 0.00 MiB Architecture: MIPS Hash algo: sha1 Hash value: 51b89b31605ee62038c8468c429af091dfc75ec7 Image 3 (fdt@ocelot_pcb123) Description: MSCC Ocelot PCB123 Device Tree Created: Tue Sep 29 05:19:40 2020 Type: Flat Device Tree Compression: uncompressed Data Size: 4639 Bytes = 4.53 KiB = 0.00 MiB Architecture: MIPS Hash algo: sha1 Hash value: be2724f58b66c316a61da7c11ced633f4e7e86c7 Image 4 (fdt@ocelot_pcb120) Description: MSCC Ocelot PCB120 Device Tree Created: Tue Sep 29 05:19:40 2020 Type: Flat Device Tree Compression: uncompressed Data Size: 5398 Bytes = 5.27 KiB = 0.01 MiB Architecture: MIPS Hash algo: sha1 Hash value: 2a757b83ef9e9d35fb6c43bdbde70d311b3e4555 Image 5 (fdt@xilfpga) Description: MIPSfpga (xilfpga) Device Tree Created: Tue Sep 29 05:19:40 2020 Type: Flat Device Tree Compression: uncompressed Data Size: 2708 Bytes = 2.64 KiB = 0.00 MiB Architecture: MIPS Hash algo: sha1 Hash value: 63d058b780f65e22da30f0a183433765f1807f1d Default Configuration: 'conf@default' Configuration 0 (conf@default) Description: Generic Linux kernel Kernel: kernel@0 Configuration 1 (conf@boston) Description: Boston Linux kernel Kernel: kernel@0 FDT: fdt@boston Configuration 2 (conf@ni169445) Description: NI 169445 Linux Kernel Kernel: kernel@0 FDT: fdt@ni169445 Configuration 3 (conf@ocelot_pcb123) Description: Ocelot Linux kernel Kernel: kernel@0 FDT: fdt@ocelot_pcb123 Configuration 4 (conf@ocelot_pcb120) Description: Ocelot Linux kernel Kernel: kernel@0 FDT: fdt@ocelot_pcb120 Configuration 5 (conf@xilfpga) Description: MIPSfpga Linux kernel Kernel: kernel@0 FDT: fdt@xilfpga Completed OK # rm -rf /kisskb/build/linus_mips-defconfig_mips-gcc4.9 # Build took: 0:02:05.575536