# git rev-parse -q --verify 8e0d0ad206f08506c893326ca7c9c3d9cc042cef^{commit}
8e0d0ad206f08506c893326ca7c9c3d9cc042cef
already have revision, skipping fetch
# git checkout -q -f -B kisskb 8e0d0ad206f08506c893326ca7c9c3d9cc042cef
# git clean -qxdf
# < git log -1
# commit 8e0d0ad206f08506c893326ca7c9c3d9cc042cef
# Author: Linus Torvalds <torvalds@linux-foundation.org>
# Date:   Tue Oct 15 09:56:36 2019 -0700
# 
#     sparc64: disable fast-GUP due to unexplained oopses
#     
#     HAVE_FAST_GUP enables the lockless quick page table walker for simple
#     cases, and is a nice optimization for some random loads that can then
#     use get_user_pages_fast() rather than the more careful page walker.
#     
#     However, for some unexplained reason, it seems to be subtly broken on
#     sparc64.  The breakage is only with some compiler versions and some
#     hardware, and nobody seems to have figured out what triggers it,
#     although there's a simple reprodicer for the problem when it does
#     trigger.
#     
#     The problem was introduced with the conversion to the generic GUP code
#     in commit 7b9afb86b632 ("sparc64: use the generic get_user_pages_fast
#     code"), but nothing looks obviously wrong in that conversion.  It may be
#     a compiler bug that just hits us with the code reorganization.  Or it
#     may be something very specific to sparc64.
#     
#     This disables HAVE_FAST_GUP entirely.  That makes things like futexes a
#     bit slower, but at least they work.  If we can figure out the trigger,
#     that would be lovely, but it's been three months already..
#     
#     Link: https://lore.kernel.org/lkml/20190717215956.GA30369@altlinux.org/
#     Fixes: 7b9afb86b632 ("sparc64: use the generic get_user_pages_fast code")
#     Reported-by: Dmitry V Levin <ldv@altlinux.org>
#     Reported-by: Anatoly Pugachev <matorola@gmail.com>
#     Requested-by: Meelis Roos <mroos@linux.ee>
#     Suggested-by: Christoph Hellwig <hch@infradead.org>
#     Cc: David Miller <davem@davemloft.net>
#     Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
# < /opt/cross/kisskb/gcc-4.6.3-nolibc/sh4-linux/bin/sh4-linux-gcc --version
# < /opt/cross/kisskb/gcc-4.6.3-nolibc/sh4-linux/bin/sh4-linux-ld --version
# < git log --format=%s --max-count=1 8e0d0ad206f08506c893326ca7c9c3d9cc042cef
# < make -s -j 24 ARCH=sh O=/kisskb/build/linus_se7206_defconfig_sh4 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/sh4-linux/bin/sh4-linux-  se7206_defconfig
# make -s -j 24 ARCH=sh O=/kisskb/build/linus_se7206_defconfig_sh4 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/sh4-linux/bin/sh4-linux-  
  Generating include/generated/machtypes.h
<stdin>:1511:2: warning: #warning syscall clone3 not implemented [-Wcpp]
/kisskb/src/arch/sh/kernel/cpu/sh2a/../../entry-common.S: Assembler messages:
/kisskb/src/arch/sh/kernel/cpu/sh2a/../../entry-common.S:385: Warning: overflow in branch to syscall_exit_work; converted into longer instruction sequence
/kisskb/src/arch/sh/kernel/cpu/sh2a/../../entry-common.S:388: Warning: overflow in branch to syscall_exit_work; converted into longer instruction sequence
/kisskb/src/kernel/rcu/srcutree.c: In function 'init_srcu_struct_fields':
/kisskb/src/kernel/rcu/srcutree.c:121:34: warning: 'levelspread[<Ud140>]' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/kernel/rcu/srcutree.c:88:6: note: 'levelspread[<Ud140>]' was declared here
/kisskb/src/kernel/printk/printk.c: In function 'devkmsg_sysctl_set_loglvl':
/kisskb/src/kernel/printk/printk.c:204:16: warning: 'old' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/fs/proc/inode.c: In function 'proc_reg_open':
/kisskb/src/include/linux/list.h:65:12: warning: 'pdeo' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/fs/proc/inode.c:338:21: note: 'pdeo' was declared here
/kisskb/src/drivers/sh/clk/cpg.c: In function 'r8':
/kisskb/src/drivers/sh/clk/cpg.c:41:2: warning: passing argument 1 of 'ioread8' discards 'const' qualifier from pointer target type [enabled by default]
/kisskb/src/include/asm-generic/iomap.h:29:21: note: expected 'void *' but argument is of type 'const void *'
/kisskb/src/drivers/sh/clk/cpg.c: In function 'r16':
/kisskb/src/drivers/sh/clk/cpg.c:46:2: warning: passing argument 1 of 'ioread16' discards 'const' qualifier from pointer target type [enabled by default]
/kisskb/src/include/asm-generic/iomap.h:30:21: note: expected 'void *' but argument is of type 'const void *'
/kisskb/src/drivers/sh/clk/cpg.c: In function 'r32':
/kisskb/src/drivers/sh/clk/cpg.c:51:2: warning: passing argument 1 of 'ioread32' discards 'const' qualifier from pointer target type [enabled by default]
/kisskb/src/include/asm-generic/iomap.h:32:21: note: expected 'void *' but argument is of type 'const void *'
Completed OK
# rm -rf /kisskb/build/linus_se7206_defconfig_sh4
# Build took: 0:00:41.181776