# 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 # 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 # Reported-by: Anatoly Pugachev # Requested-by: Meelis Roos # Suggested-by: Christoph Hellwig # Cc: David Miller # Signed-off-by: Linus Torvalds # < /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 120 ARCH=arm O=/kisskb/build/linus_at91_dt_defconfig_arm CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/arm-unknown-linux-gnueabi/bin/arm-unknown-linux-gnueabi- at91_dt_defconfig # make -s -j 120 ARCH=arm O=/kisskb/build/linus_at91_dt_defconfig_arm CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/arm-unknown-linux-gnueabi/bin/arm-unknown-linux-gnueabi- /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/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/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/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/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/lib/mpi/mpicoder.c: In function 'mpi_read_raw_from_sgl': /kisskb/src/lib/mpi/mpicoder.c:336:12: warning: 'buff' may be used uninitialized in this function [-Wuninitialized] /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/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/drivers/mtd/ubi/eba.c: In function 'try_write_vid_and_data': /kisskb/src/drivers/mtd/ubi/eba.c:988:7: warning: 'opnum' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/rtc/rtc-rv3029c2.c: In function 'rv3029_probe': /kisskb/src/drivers/rtc/rtc-rv3029c2.c:660:3: warning: 'elem' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/drivers/rtc/rtc-rv3029c2.c:639:40: note: 'elem' was declared here /kisskb/src/net/mac80211/tx.c: In function 'ieee80211_build_hdr': /kisskb/src/net/mac80211/tx.c:2519:27: warning: 'chanctx_conf' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/lib/rhashtable.c: In function 'rht_deferred_worker': /kisskb/src/include/linux/rhashtable.h:110:10: warning: 'next' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/lib/rhashtable.c:222:28: note: 'next' was declared here /kisskb/src/drivers/usb/core/devio.c: In function 'async_completed': /kisskb/src/drivers/usb/core/devio.c:625:23: warning: 'errno' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/net/mac80211/mlme.c: In function 'ieee80211_rx_mgmt_beacon': /kisskb/src/net/mac80211/mlme.c:1576:3: warning: 'pwr_level_cisco' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/net/mac80211/mlme.c:1533:6: note: 'pwr_level_cisco' was declared here /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/net/wireless/nl80211.c: In function 'nl80211_vendor_cmd_dump': /kisskb/src/net/wireless/nl80211.c:13138:33: warning: 'wdev' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/net/wireless/nl80211.c:13108:21: warning: 'rdev' may be used uninitialized in this function [-Wuninitialized] WARNING: "return_address" [vmlinux] is a static EXPORT_SYMBOL_GPL Completed OK # rm -rf /kisskb/build/linus_at91_dt_defconfig_arm # Build took: 0:00:35.572534