# 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 <Jason@zx2c4.com>
# 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 <chris@chris-wilson.co.uk>
#     Reported-by: Harald Arnesen <harald@skogtun.org>
#     Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
#     Reviewed-by: Peter Xu <peterx@redhat.com>
#     Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
#     Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
# < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/nds32le-linux/bin/nds32le-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/nds32le-linux/bin/nds32le-linux-ld --version
# < git log --format=%s --max-count=1 a4d63c3732f1a0c91abcf5b7f32b4ef7dcd82025
# < make -s -j 48 ARCH=nds32 O=/kisskb/build/linus_nds32-allyesconfig_nds32le-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/nds32le-linux/bin/nds32le-linux-  allyesconfig
# < make -s -j 48 ARCH=nds32 O=/kisskb/build/linus_nds32-allyesconfig_nds32le-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/nds32le-linux/bin/nds32le-linux-  help
# make -s -j 48 ARCH=nds32 O=/kisskb/build/linus_nds32-allyesconfig_nds32le-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/nds32le-linux/bin/nds32le-linux-  olddefconfig
# make -s -j 48 ARCH=nds32 O=/kisskb/build/linus_nds32-allyesconfig_nds32le-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/nds32le-linux/bin/nds32le-linux-  
<stdin>:1511:2: warning: #warning syscall clone3 not implemented [-Wcpp]
/kisskb/src/drivers/input/joystick/analog.c:160:2: warning: #warning Precise timer not defined for this architecture. [-Wcpp]
 #warning Precise timer not defined for this architecture.
  ^~~~~~~
In file included from /kisskb/src/include/linux/printk.h:405,
                 from /kisskb/src/include/linux/kernel.h:15,
                 from /kisskb/src/include/linux/clk.h:13,
                 from /kisskb/src/drivers/crypto/sa2ul.c:11:
/kisskb/src/drivers/crypto/sa2ul.c: In function 'sa_sha_init':
/kisskb/src/drivers/crypto/sa2ul.c:1486:33: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
   crypto_ahash_digestsize(tfm), (u64)rctx);
                                 ^
/kisskb/src/include/linux/dynamic_debug.h:129:15: note: in definition of macro '__dynamic_func_call'
   func(&id, ##__VA_ARGS__);  \
               ^~~~~~~~~~~
/kisskb/src/include/linux/dynamic_debug.h:161:2: note: in expansion of macro '_dynamic_func_call'
  _dynamic_func_call(fmt,__dynamic_dev_dbg,   \
  ^~~~~~~~~~~~~~~~~~
/kisskb/src/include/linux/dev_printk.h:115:2: note: in expansion of macro 'dynamic_dev_dbg'
  dynamic_dev_dbg(dev, dev_fmt(fmt), ##__VA_ARGS__)
  ^~~~~~~~~~~~~~~
/kisskb/src/drivers/crypto/sa2ul.c:1485:2: note: in expansion of macro 'dev_dbg'
  dev_dbg(sa_k3_dev, "init: digest size: %d, rctx=%llx\n",
  ^~~~~~~
WARNING: modpost: EXPORT symbol "copy_page" [vmlinux] version generation failed, symbol will not be versioned.
WARNING: modpost: EXPORT symbol "clear_page" [vmlinux] version generation failed, symbol will not be versioned.
Completed OK
# rm -rf /kisskb/build/linus_nds32-allyesconfig_nds32le-gcc8
# Build took: 0:12:41.585090