Buildresult: linus/mips-allnoconfig/mipsel-gcc5 built on Jun 4 2019, 21:07

kisskb

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Status:	OK
Date/Time:	Jun 4 2019, 21:07
Duration:	0:00:15.480323
Builder:	ka1
Revision:	rcu: locking and unlocking need to always be at least barriers (`66be4e66a7f422128748e3c3ef6ee72b20a6197b)`
Target:	linus/mips-allnoconfig/mipsel-gcc5
Branch:	linus
Compiler:	mipsel-gcc5 (mipsel-linux-gcc.br_real (Buildroot 2016.11-git-00613-ge98b4dd) 5.4.0 / GNU ld (GNU Binutils) 2.26.1)
Config:	allnoconfig (download)
Log:	Download original No warnings found in log. Full Log # git rev-parse -q --verify 66be4e66a7f422128748e3c3ef6ee72b20a6197b^{commit} 66be4e66a7f422128748e3c3ef6ee72b20a6197b already have revision, skipping fetch # git checkout -q -f -B kisskb 66be4e66a7f422128748e3c3ef6ee72b20a6197b # git clean -qxdf # < git log -1 # commit 66be4e66a7f422128748e3c3ef6ee72b20a6197b # Author: Linus Torvalds <torvalds@linux-foundation.org> # Date: Mon Jun 3 13:26:20 2019 -0700 # # rcu: locking and unlocking need to always be at least barriers # # Herbert Xu pointed out that commit bb73c52bad36 ("rcu: Don't disable # preemption for Tiny and Tree RCU readers") was incorrect in making the # preempt_disable/enable() be conditional on CONFIG_PREEMPT_COUNT. # # If CONFIG_PREEMPT_COUNT isn't enabled, the preemption enable/disable is # a no-op, but still is a compiler barrier. # # And RCU locking still _needs_ that compiler barrier. # # It is simply fundamentally not true that RCU locking would be a complete # no-op: we still need to guarantee (for example) that things that can # trap and cause preemption cannot migrate into the RCU locked region. # # The way we do that is by making it a barrier. # # See for example commit 386afc91144b ("spinlocks and preemption points # need to be at least compiler barriers") from back in 2013 that had # similar issues with spinlocks that become no-ops on UP: they must still # constrain the compiler from moving other operations into the critical # region. # # Now, it is true that a lot of RCU operations already use READ_ONCE() and # WRITE_ONCE() (which in practice likely would never be re-ordered wrt # anything remotely interesting), but it is also true that that is not # globally the case, and that it's not even necessarily always possible # (ie bitfields etc). # # Reported-by: Herbert Xu <herbert@gondor.apana.org.au> # Fixes: bb73c52bad36 ("rcu: Don't disable preemption for Tiny and Tree RCU readers") # Cc: stable@kernel.org # Cc: Boqun Feng <boqun.feng@gmail.com> # Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> # Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> # < /opt/cross/kisskb/br-mipsel-o32-full-2016.08-613-ge98b4dd/bin/mipsel-linux-gcc --version # < /opt/cross/kisskb/br-mipsel-o32-full-2016.08-613-ge98b4dd/bin/mipsel-linux-ld --version # < git log --format=%s --max-count=1 66be4e66a7f422128748e3c3ef6ee72b20a6197b # < make -s -j 48 ARCH=mips O=/kisskb/build/linus_mips-allnoconfig_mipsel CROSS_COMPILE=/opt/cross/kisskb/br-mipsel-o32-full-2016.08-613-ge98b4dd/bin/mipsel-linux- allnoconfig # make -s -j 48 ARCH=mips O=/kisskb/build/linus_mips-allnoconfig_mipsel CROSS_COMPILE=/opt/cross/kisskb/br-mipsel-o32-full-2016.08-613-ge98b4dd/bin/mipsel-linux- FIT description: Linux 5.2.0-rc3+ Created: Tue Jun 4 21:08:03 2019 Image 0 (kernel@0) Description: Linux 5.2.0-rc3+ Created: Tue Jun 4 21:08:03 2019 Type: Kernel Image Compression: gzip compressed Data Size: 650160 Bytes = 634.92 KiB = 0.62 MiB Architecture: MIPS OS: Linux Load Address: 0x80100000 Entry Point: 0x80223d40 Hash algo: sha1 Hash value: 3c9836740b0a73c4eb994a41cd82b97e4238ea8a Default Configuration: 'conf@default' Configuration 0 (conf@default) Description: Generic Linux kernel Kernel: kernel@0 Completed OK # rm -rf /kisskb/build/linus_mips-allnoconfig_mipsel # Build took: 0:00:15.480323

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