# git rev-parse -q --verify 7b4ea9456dd3f73238408126ab00f1d906963d81^{commit}
7b4ea9456dd3f73238408126ab00f1d906963d81
already have revision, skipping fetch
# git checkout -q -f -B kisskb 7b4ea9456dd3f73238408126ab00f1d906963d81
# git clean -qxdf
# < git log -1
# commit 7b4ea9456dd3f73238408126ab00f1d906963d81
# Author: Linus Torvalds <torvalds@linux-foundation.org>
# Date:   Thu Aug 6 12:02:58 2020 -0700
# 
#     Revert "x86/mm/64: Do not sync vmalloc/ioremap mappings"
#     
#     This reverts commit 8bb9bf242d1fee925636353807c511d54fde8986.
#     
#     It seems the vmalloc page tables aren't always preallocated in all
#     situations, because Jason Donenfeld reports an oops with this commit:
#     
#       BUG: unable to handle page fault for address: ffffe8ffffd00608
#       #PF: supervisor read access in kernel mode
#       #PF: error_code(0x0000) - not-present page
#       PGD 0 P4D 0
#       Oops: 0000 [#1] PREEMPT SMP
#       CPU: 2 PID: 22 Comm: kworker/2:0 Not tainted 5.8.0+ #154
#       RIP: process_one_work+0x2c/0x2d0
#       Code: 41 56 41 55 41 54 55 48 89 f5 53 48 89 fb 48 83 ec 08 48 8b 06 4c 8b 67 40 49 89 c6 45 30 f6 a8 04 b8 00 00 00 00 4c 0f 44 f0 <49> 8b 46 08 44 8b a8 00 01 05
#       Call Trace:
#        worker_thread+0x4b/0x3b0
#        ? rescuer_thread+0x360/0x360
#        kthread+0x116/0x140
#        ? __kthread_create_worker+0x110/0x110
#        ret_from_fork+0x1f/0x30
#       CR2: ffffe8ffffd00608
#     
#     and that page fault address is right in that vmalloc space, and we
#     clearly don't have a PGD/P4D entry for it.
#     
#     Looking at the "Code:" line, the actual fault seems to come from the
#     'pwq->wq' dereference at the top of the process_one_work() function:
#     
#             struct pool_workqueue *pwq = get_work_pwq(work);
#             struct worker_pool *pool = worker->pool;
#             bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE;
#     
#     so 'struct pool_workqueue *pwq' is the allocation that hasn't been
#     synchronized across CPUs.
#     
#     Just revert for now, while Joerg figures out the cause.
#     
#     Reported-and-bisected-by: Jason A. Donenfeld <Jason@zx2c4.com>
#     Acked-by: Ingo Molnar <mingo@kernel.org>
#     Acked-by: Joerg Roedel <jroedel@suse.de>
#     Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
# < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/x86_64-linux/bin/x86_64-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/x86_64-linux/bin/x86_64-linux-ld --version
# < git log --format=%s --max-count=1 7b4ea9456dd3f73238408126ab00f1d906963d81
# < make -s -j 48 ARCH=x86_64 O=/kisskb/build/linus-rand_x86_64-randconfig_x86_64-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/x86_64-linux/bin/x86_64-linux-  randconfig
KCONFIG_SEED=0x43458AF7
# Added to kconfig CONFIG_STANDALONE=y
# Added to kconfig CONFIG_PREVENT_FIRMWARE_BUILD=y
# Added to kconfig CONFIG_CC_STACKPROTECTOR_STRONG=n
# Added to kconfig CONFIG_GCC_PLUGINS=n
# Added to kconfig CONFIG_GCC_PLUGIN_CYC_COMPLEXITY=n
# Added to kconfig CONFIG_GCC_PLUGIN_SANCOV=n
# Added to kconfig CONFIG_GCC_PLUGIN_LATENT_ENTROPY=n
# < make -s -j 48 ARCH=x86_64 O=/kisskb/build/linus-rand_x86_64-randconfig_x86_64-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/x86_64-linux/bin/x86_64-linux-  help
# make -s -j 48 ARCH=x86_64 O=/kisskb/build/linus-rand_x86_64-randconfig_x86_64-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/x86_64-linux/bin/x86_64-linux-  olddefconfig
.config:5270:warning: override: reassigning to symbol STANDALONE
# make -s -j 48 ARCH=x86_64 O=/kisskb/build/linus-rand_x86_64-randconfig_x86_64-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/x86_64-linux/bin/x86_64-linux-  
/bin/sh: 1: zstd: not found
cat: write error: Broken pipe
make[3]: *** [/kisskb/src/arch/x86/boot/compressed/Makefile:150: arch/x86/boot/compressed/vmlinux.bin.zst] Error 127
make[3]: *** Deleting file 'arch/x86/boot/compressed/vmlinux.bin.zst'
make[3]: *** Waiting for unfinished jobs....
make[2]: *** [/kisskb/src/arch/x86/boot/Makefile:115: arch/x86/boot/compressed/vmlinux] Error 2
make[1]: *** [arch/x86/Makefile:265: bzImage] Error 2
make[1]: *** Waiting for unfinished jobs....
make: *** [Makefile:185: __sub-make] Error 2
Command 'make -s -j 48 ARCH=x86_64 O=/kisskb/build/linus-rand_x86_64-randconfig_x86_64-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/x86_64-linux/bin/x86_64-linux-  ' returned non-zero exit status 2
# rm -rf /kisskb/build/linus-rand_x86_64-randconfig_x86_64-gcc8
# Build took: 0:03:55.317655