Buildresult: linus/mips-allmodconfig/mips-gcc8 built on Jul 17 2021, 12:21

kisskb

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Status:	OK
Date/Time:	Jul 17 2021, 12:21
Duration:	0:26:47.590238
Builder:	ka2
Revision:	Revert "signal: Allow tasks to cache one sigqueue struct" (`b4b27b9eed8ebdbf9f3046197d29d733c8c944f3)`
Target:	linus/mips-allmodconfig/mips-gcc8
Branch:	linus
Compiler:	mips-gcc8 (mips-linux-gcc (GCC) 8.1.0 / GNU ld (GNU Binutils) 2.30)
Config:	allmodconfig (download)
Log:	Download original Possible warnings (5) .config:13061:warning: override: reassigning to symbol MIPS_CPS_NS16550_SHIFT 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. arch/mips/include/asm/sibyte/bcm1480_scd.h:261: warning: "M_SPC_CFG_CLEAR" redefined arch/mips/include/asm/sibyte/bcm1480_scd.h:262: warning: "M_SPC_CFG_ENABLE" redefined Full Log # git rev-parse -q --verify b4b27b9eed8ebdbf9f3046197d29d733c8c944f3^{commit} b4b27b9eed8ebdbf9f3046197d29d733c8c944f3 already have revision, skipping fetch # git checkout -q -f -B kisskb b4b27b9eed8ebdbf9f3046197d29d733c8c944f3 # git clean -qxdf # < git log -1 # commit b4b27b9eed8ebdbf9f3046197d29d733c8c944f3 # Author: Linus Torvalds <torvalds@linux-foundation.org> # Date: Sun Jun 27 13:32:54 2021 -0700 # # Revert "signal: Allow tasks to cache one sigqueue struct" # # This reverts commits 4bad58ebc8bc4f20d89cff95417c9b4674769709 (and # 399f8dd9a866e107639eabd3c1979cd526ca3a98, which tried to fix it). # # I do not believe these are correct, and I'm about to release 5.13, so am # reverting them out of an abundance of caution. # # The locking is odd, and appears broken. # # On the allocation side (in __sigqueue_alloc()), the locking is somewhat # straightforward: it depends on sighand->siglock. Since one caller # doesn't hold that lock, it further then tests 'sigqueue_flags' to avoid # the case with no locks held. # # On the freeing side (in sigqueue_cache_or_free()), there is no locking # at all, and the logic instead depends on 'current' being a single # thread, and not able to race with itself. # # To make things more exciting, there's also the data race between freeing # a signal and allocating one, which is handled by using WRITE_ONCE() and # READ_ONCE(), and being mutually exclusive wrt the initial state (ie # freeing will only free if the old state was NULL, while allocating will # obviously only use the value if it was non-NULL, so only one or the # other will actually act on the value). # # However, while the free->alloc paths do seem mutually exclusive thanks # to just the data value dependency, it's not clear what the memory # ordering constraints are on it. Could writes from the previous # allocation possibly be delayed and seen by the new allocation later, # causing logical inconsistencies? # # So it's all very exciting and unusual. # # And in particular, it seems that the freeing side is incorrect in # depending on "current" being single-threaded. Yes, 'current' is a # single thread, but in the presense of asynchronous events even a single # thread can have data races. # # And such asynchronous events can and do happen, with interrupts causing # signals to be flushed and thus free'd (for example - sending a # SIGCONT/SIGSTOP can happen from interrupt context, and can flush # previously queued process control signals). # # So regardless of all the other questions about the memory ordering and # locking for this new cached allocation, the sigqueue_cache_or_free() # assumptions seem to be fundamentally incorrect. # # It may be that people will show me the errors of my ways, and tell me # why this is all safe after all. We can reinstate it if so. But my # current belief is that the WRITE_ONCE() that sets the cached entry needs # to be a smp_store_release(), and the READ_ONCE() that finds a cached # entry needs to be a smp_load_acquire() to handle memory ordering # correctly. # # And the sequence in sigqueue_cache_or_free() would need to either use a # lock or at least be interrupt-safe some way (perhaps by using something # like the percpu 'cmpxchg': it doesn't need to be SMP-safe, but like the # percpu operations it needs to be interrupt-safe). # # Fixes: 399f8dd9a866 ("signal: Prevent sigqueue caching after task got released") # Fixes: 4bad58ebc8bc ("signal: Allow tasks to cache one sigqueue struct") # Cc: Thomas Gleixner <tglx@linutronix.de> # Cc: Peter Zijlstra <peterz@infradead.org> # Cc: Oleg Nesterov <oleg@redhat.com> # Cc: Christian Brauner <christian.brauner@ubuntu.com> # Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> # < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/mips-linux/bin/mips-linux-gcc --version # < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/mips-linux/bin/mips-linux-ld --version # < git log --format=%s --max-count=1 b4b27b9eed8ebdbf9f3046197d29d733c8c944f3 # < make -s -j 48 ARCH=mips O=/kisskb/build/linus_mips-allmodconfig_mips-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/mips-linux/bin/mips-linux- allmodconfig # Added to kconfig CONFIG_BUILD_DOCSRC=n # Added to kconfig CONFIG_MODULE_SIG=n # Added to kconfig CONFIG_SAMPLES=n # Added to kconfig CONFIG_MIPS_CPS_NS16550_BASE=0x1b0003f8 # Added to kconfig CONFIG_MIPS_CPS_NS16550_SHIFT=0 # < make -s -j 48 ARCH=mips O=/kisskb/build/linus_mips-allmodconfig_mips-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/mips-linux/bin/mips-linux- help # make -s -j 48 ARCH=mips O=/kisskb/build/linus_mips-allmodconfig_mips-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/mips-linux/bin/mips-linux- olddefconfig .config:13061:warning: override: reassigning to symbol MIPS_CPS_NS16550_SHIFT # make -s -j 48 ARCH=mips O=/kisskb/build/linus_mips-allmodconfig_mips-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/mips-linux/bin/mips-linux- /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/arch/mips/include/asm/sibyte/sb1250.h:28, from /kisskb/src/drivers/watchdog/sb_wdog.c:58: /kisskb/src/arch/mips/include/asm/sibyte/bcm1480_scd.h:261: warning: "M_SPC_CFG_CLEAR" redefined #define M_SPC_CFG_CLEAR M_BCM1480_SPC_CFG_CLEAR In file included from /kisskb/src/arch/mips/include/asm/sibyte/sb1250.h:27, from /kisskb/src/drivers/watchdog/sb_wdog.c:58: /kisskb/src/arch/mips/include/asm/sibyte/sb1250_scd.h:392: note: this is the location of the previous definition #define M_SPC_CFG_CLEAR _SB_MAKEMASK1(32) In file included from /kisskb/src/arch/mips/include/asm/sibyte/sb1250.h:28, from /kisskb/src/drivers/watchdog/sb_wdog.c:58: /kisskb/src/arch/mips/include/asm/sibyte/bcm1480_scd.h:262: warning: "M_SPC_CFG_ENABLE" redefined #define M_SPC_CFG_ENABLE M_BCM1480_SPC_CFG_ENABLE In file included from /kisskb/src/arch/mips/include/asm/sibyte/sb1250.h:27, from /kisskb/src/drivers/watchdog/sb_wdog.c:58: /kisskb/src/arch/mips/include/asm/sibyte/sb1250_scd.h:393: note: this is the location of the previous definition #define M_SPC_CFG_ENABLE _SB_MAKEMASK1(33) FIT description: Linux 5.13.0-rc7+ Created: Sat Jul 17 12:44:53 2021 Image 0 (kernel) Description: Linux 5.13.0-rc7+ Created: Sat Jul 17 12:44:53 2021 Type: Kernel Image Compression: gzip compressed Data Size: 10293195 Bytes = 10051.95 KiB = 9.82 MiB Architecture: MIPS OS: Linux Load Address: 0x84000000 Entry Point: 0x8548b3a0 Hash algo: sha1 Hash value: a3c80af69fb470f8d0c03ad4c0343c3d18cf1c69 Image 1 (fdt-boston) Description: img,boston Device Tree Created: Sat Jul 17 12:44:53 2021 Type: Flat Device Tree Compression: uncompressed Data Size: 3793 Bytes = 3.70 KiB = 0.00 MiB Architecture: MIPS Hash algo: sha1 Hash value: 4799f50d688573234da6e9d7701234d394759ef4 Image 2 (fdt-ni169445) Description: NI 169445 device tree Created: Sat Jul 17 12:44:53 2021 Type: Flat Device Tree Compression: uncompressed Data Size: 1871 Bytes = 1.83 KiB = 0.00 MiB Architecture: MIPS Hash algo: sha1 Hash value: 51b89b31605ee62038c8468c429af091dfc75ec7 Image 3 (fdt-ocelot_pcb123) Description: MSCC Ocelot PCB123 Device Tree Created: Sat Jul 17 12:44:53 2021 Type: Flat Device Tree Compression: uncompressed Data Size: 4659 Bytes = 4.55 KiB = 0.00 MiB Architecture: MIPS Hash algo: sha1 Hash value: 5bcb6e4f21e8e5372544aa130b3bd097355a9050 Image 4 (fdt-ocelot_pcb120) Description: MSCC Ocelot PCB120 Device Tree Created: Sat Jul 17 12:44:53 2021 Type: Flat Device Tree Compression: uncompressed Data Size: 5418 Bytes = 5.29 KiB = 0.01 MiB Architecture: MIPS Hash algo: sha1 Hash value: 93d882f2009a217e0fa9dab94788535ed2be8476 Image 5 (fdt-luton_pcb091) Description: MSCC Luton PCB091 Device Tree Created: Sat Jul 17 12:44:53 2021 Type: Flat Device Tree Compression: uncompressed Data Size: 2303 Bytes = 2.25 KiB = 0.00 MiB Architecture: MIPS Hash algo: sha1 Hash value: daa8a8147bbce692d81383af7b748a763212bb24 Image 6 (fdt-jaguar2_pcb110) Description: MSCC Jaguar2 PCB110 Device Tree Created: Sat Jul 17 12:44:53 2021 Type: Flat Device Tree Compression: uncompressed Data Size: 7509 Bytes = 7.33 KiB = 0.01 MiB Architecture: MIPS Hash algo: sha1 Hash value: 73c08d98d7aaf64b3e82483d33954c951cfb8067 Image 7 (fdt-jaguar2_pcb111) Description: MSCC Jaguar2 PCB111 Device Tree Created: Sat Jul 17 12:44:53 2021 Type: Flat Device Tree Compression: uncompressed Data Size: 4581 Bytes = 4.47 KiB = 0.00 MiB Architecture: MIPS Hash algo: sha1 Hash value: d8ab1c8279a311c512005c256502f85a33651fe9 Image 8 (fdt-serval_pcb105) Description: MSCC Serval PCB105 Device Tree Created: Sat Jul 17 12:44:53 2021 Type: Flat Device Tree Compression: uncompressed Data Size: 4545 Bytes = 4.44 KiB = 0.00 MiB Architecture: MIPS Hash algo: sha1 Hash value: 372c736c817c1313650e487910d7b94a32816bd7 Image 9 (fdt-xilfpga) Description: MIPSfpga (xilfpga) Device Tree Created: Sat Jul 17 12:44:53 2021 Type: Flat Device Tree Compression: uncompressed Data Size: 2708 Bytes = 2.64 KiB = 0.00 MiB Architecture: MIPS Hash algo: sha1 Hash value: 63d058b780f65e22da30f0a183433765f1807f1d Default Configuration: 'conf-default' Configuration 0 (conf-default) Description: Generic Linux kernel Kernel: kernel Configuration 1 (conf-boston) Description: Boston Linux kernel Kernel: kernel FDT: fdt-boston Configuration 2 (conf-ni169445) Description: NI 169445 Linux Kernel Kernel: kernel FDT: fdt-ni169445 Configuration 3 (conf-ocelot_pcb123) Description: Ocelot Linux kernel Kernel: kernel FDT: fdt-ocelot_pcb123 Configuration 4 (conf-ocelot_pcb120) Description: Ocelot Linux kernel Kernel: kernel FDT: fdt-ocelot_pcb120 Configuration 5 (pcb091) Description: Luton Linux kernel Kernel: kernel FDT: fdt-luton_pcb091 Configuration 6 (pcb110) Description: Jaguar2 Linux kernel Kernel: kernel Init Ramdisk: ramdisk FDT: fdt-jaguar2_pcb110 Configuration 7 (pcb111) Description: Jaguar2 Linux kernel Kernel: kernel Init Ramdisk: ramdisk FDT: fdt-jaguar2_pcb111 Configuration 8 (pcb105) Description: Serval Linux kernel Kernel: kernel Init Ramdisk: ramdisk FDT: fdt-serval_pcb105 Configuration 9 (conf-xilfpga) Description: MIPSfpga Linux kernel Kernel: kernel FDT: fdt-xilfpga Completed OK # rm -rf /kisskb/build/linus_mips-allmodconfig_mips-gcc8 # Build took: 0:26:47.590238

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