# 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/arm-unknown-linux-gnueabi/bin/arm-unknown-linux-gnueabi-gcc --version
# < /opt/cross/kisskb/gcc-4.6.3-nolibc/arm-unknown-linux-gnueabi/bin/arm-unknown-linux-gnueabi-ld --version
# < git log --format=%s --max-count=1 8e0d0ad206f08506c893326ca7c9c3d9cc042cef
# < make -s -j 48 ARCH=arm O=/kisskb/build/linus_shmobile_defconfig_arm CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/arm-unknown-linux-gnueabi/bin/arm-unknown-linux-gnueabi-  shmobile_defconfig
# make -s -j 48 ARCH=arm O=/kisskb/build/linus_shmobile_defconfig_arm CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/arm-unknown-linux-gnueabi/bin/arm-unknown-linux-gnueabi-  
/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/kernel/rcu/srcutree.c: In function 'init_srcu_struct_fields':
/kisskb/src/kernel/rcu/srcutree.c:140:32: warning: 'levelspread[<U 640>]' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/kernel/rcu/srcutree.c:88:6: note: 'levelspread[<U 640>]' was declared here
/kisskb/src/ipc/shm.c: In function 'ksys_shmdt':
/kisskb/src/ipc/shm.c:1712:59: warning: 'file' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/drivers/i2c/busses/i2c-sh_mobile.c: In function 'sh_mobile_i2c_isr':
/kisskb/src/drivers/i2c/busses/i2c-sh_mobile.c:399:26: warning: 'data' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/drivers/i2c/busses/i2c-sh_mobile.c:372:16: note: 'data' was declared here
/kisskb/src/sound/core/pcm_iec958.c: In function 'create_iec958_consumer':
/kisskb/src/sound/core/pcm_iec958.c:77:9: warning: 'ws' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/drivers/gpio/gpiolib-of.c: In function 'of_gpiochip_add':
/kisskb/src/drivers/gpio/gpiolib-of.c:626:8: warning: 'dflags' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/drivers/gpio/gpiolib-of.c:612:19: note: 'dflags' was declared here
/kisskb/src/drivers/gpio/gpiolib-of.c:626:8: warning: 'lflags' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/drivers/gpio/gpiolib-of.c:611:16: note: 'lflags' was declared here
/kisskb/src/net/core/gen_stats.c: In function '__gnet_stats_copy_basic':
/kisskb/src/net/core/gen_stats.c:157:19: warning: 'seq' 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/gpu/drm/drm_dp_mst_topology.c: In function 'drm_dp_sideband_msg_build':
/kisskb/src/drivers/gpu/drm/drm_dp_mst_topology.c:429:23: warning: 'hdrlen' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/net/core/dev.c: In function 'validate_xmit_skb_list':
/kisskb/src/net/core/dev.c:3407:15: warning: 'tail' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/lib/rhashtable.c: In function 'rht_deferred_worker':
/kisskb/src/lib/rhashtable.c:259:20: warning: 'next' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/lib/rhashtable.c:222:28: note: 'next' was declared here
/kisskb/src/sound/soc/soc-pcm.c: In function 'soc_pcm_trigger':
/kisskb/src/sound/soc/soc-pcm.c:1074:5: warning: 'ret' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/sound/soc/soc-pcm.c: In function 'soc_pcm_bespoke_trigger':
/kisskb/src/sound/soc/soc-pcm.c:1092:9: warning: 'ret' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/drivers/gpu/drm/drm_atomic.c: In function 'drm_atomic_check_only':
/kisskb/src/drivers/gpu/drm/drm_atomic.c:426:38: warning: 'crtc_state' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/drivers/gpu/drm/drm_atomic.c:405:25: note: 'crtc_state' was declared here
/kisskb/src/drivers/usb/host/xhci-debugfs.c: In function 'xhci_ring_open':
/kisskb/src/drivers/usb/host/xhci-debugfs.c:246:20: warning: 'f_map' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/drivers/usb/host/xhci-debugfs.c: In function 'xhci_context_open':
/kisskb/src/drivers/usb/host/xhci-debugfs.c:327:20: warning: 'f_map' may be used uninitialized in this function [-Wuninitialized]
Completed OK
# rm -rf /kisskb/build/linus_shmobile_defconfig_arm
# Build took: 0:01:02.642932