linux-kernel - Re: [PATCH v2 06/28] locking/rwlocks: Add contention detection for rwlocks

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20210209203908.GA255655@roeck-us.net>
Date:   Tue, 9 Feb 2021 12:39:08 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Ben Gardon <bgardon@...gle.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Peter Xu <peterx@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Peter Shier <pshier@...gle.com>,
        Peter Feiner <pfeiner@...gle.com>,
        Junaid Shahid <junaids@...gle.com>,
        Jim Mattson <jmattson@...gle.com>,
        Yulei Zhang <yulei.kernel@...il.com>,
        Wanpeng Li <kernellwp@...il.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Xiao Guangrong <xiaoguangrong.eric@...il.com>,
        Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Davidlohr Bueso <dbueso@...e.de>,
        Waiman Long <longman@...hat.com>
Subject: Re: [PATCH v2 06/28] locking/rwlocks: Add contention detection for
 rwlocks

On Tue, Feb 02, 2021 at 10:57:12AM -0800, Ben Gardon wrote:
> rwlocks do not currently have any facility to detect contention
> like spinlocks do. In order to allow users of rwlocks to better manage
> latency, add contention detection for queued rwlocks.
> 
> CC: Ingo Molnar <mingo@...hat.com>
> CC: Will Deacon <will@...nel.org>
> Acked-by: Peter Zijlstra <peterz@...radead.org>
> Acked-by: Davidlohr Bueso <dbueso@...e.de>
> Acked-by: Waiman Long <longman@...hat.com>
> Acked-by: Paolo Bonzini <pbonzini@...hat.com>
> Signed-off-by: Ben Gardon <bgardon@...gle.com>

When building mips:defconfig, this patch results in:

Error log:
In file included from include/linux/spinlock.h:90,
                 from include/linux/ipc.h:5,
                 from include/uapi/linux/sem.h:5,
                 from include/linux/sem.h:5,
                 from include/linux/compat.h:14,
                 from arch/mips/kernel/asm-offsets.c:12:
arch/mips/include/asm/spinlock.h:17:28: error: redefinition of 'queued_spin_unlock'
   17 | #define queued_spin_unlock queued_spin_unlock
      |                            ^~~~~~~~~~~~~~~~~~
arch/mips/include/asm/spinlock.h:22:20: note: in expansion of macro 'queued_spin_unlock'
   22 | static inline void queued_spin_unlock(struct qspinlock *lock)
      |                    ^~~~~~~~~~~~~~~~~~
In file included from include/asm-generic/qrwlock.h:17,
                 from ./arch/mips/include/generated/asm/qrwlock.h:1,
                 from arch/mips/include/asm/spinlock.h:13,
                 from include/linux/spinlock.h:90,
                 from include/linux/ipc.h:5,
                 from include/uapi/linux/sem.h:5,
                 from include/linux/sem.h:5,
                 from include/linux/compat.h:14,
                 from arch/mips/kernel/asm-offsets.c:12:
include/asm-generic/qspinlock.h:94:29: note: previous definition of 'queued_spin_unlock' was here
   94 | static __always_inline void queued_spin_unlock(struct qspinlock *lock)
      |                             ^~~~~~~~~~~~~~~~~~

Bisect log attached.

Guenter

---
# bad: [a4bfd8d46ac357c12529e4eebb6c89502b03ecc9] Add linux-next specific files for 20210209
# good: [92bf22614b21a2706f4993b278017e437f7785b3] Linux 5.11-rc7
git bisect start 'HEAD' 'v5.11-rc7'
# good: [a8eb921ba7e8e77d994a1c6c69c8ef08456ecf53] Merge remote-tracking branch 'crypto/master'
git bisect good a8eb921ba7e8e77d994a1c6c69c8ef08456ecf53
# good: [21d507c41bdf83f6afc0e02976e43c10badfc6cd] Merge remote-tracking branch 'spi/for-next'
git bisect good 21d507c41bdf83f6afc0e02976e43c10badfc6cd
# bad: [30cd4c688a3bcf324f011d7716044b1a4681efc1] Merge remote-tracking branch 'soundwire/next'
git bisect bad 30cd4c688a3bcf324f011d7716044b1a4681efc1
# bad: [c43d2173d3eb4047bb62a7a393a298a1032cce18] Merge remote-tracking branch 'drivers-x86/for-next'
git bisect bad c43d2173d3eb4047bb62a7a393a298a1032cce18
# good: [973e9d8622a6fecc52f639680cbbde1519e1fcf8] Merge remote-tracking branch 'rcu/rcu/next'
git bisect good 973e9d8622a6fecc52f639680cbbde1519e1fcf8
# bad: [7b2aaf51d499e0372cbecafad04582c71ad03c73] Merge remote-tracking branch 'kvm/next'
git bisect bad 7b2aaf51d499e0372cbecafad04582c71ad03c73
# good: [04548ed0206ca895c8edd6a078c20a218423890b] KVM: SVM: Replace hard-coded value with #define
git bisect good 04548ed0206ca895c8edd6a078c20a218423890b
# bad: [92f4d400a407235783afd4399fa26c4c665024b5] KVM: x86/xen: Fix __user pointer handling for hypercall page installation
git bisect bad 92f4d400a407235783afd4399fa26c4c665024b5
# good: [ed5e484b79e8a9b8be714bd85b6fc70bd6dc99a7] KVM: x86/mmu: Ensure forward progress when yielding in TDP MMU iter
git bisect good ed5e484b79e8a9b8be714bd85b6fc70bd6dc99a7
# bad: [f3d4b4b1dc1c5fb9ea17cac14133463bfe72f170] sched: Add cond_resched_rwlock
git bisect bad f3d4b4b1dc1c5fb9ea17cac14133463bfe72f170
# good: [f1b3b06a058bb5c636ffad0afae138fe30775881] KVM: x86/mmu: Clear dirtied pages mask bit before early break
git bisect good f1b3b06a058bb5c636ffad0afae138fe30775881
# bad: [26128cb6c7e6731fe644c687af97733adfdb5ee9] locking/rwlocks: Add contention detection for rwlocks
git bisect bad 26128cb6c7e6731fe644c687af97733adfdb5ee9
# good: [7cca2d0b7e7d9f3cd740d41afdc00051c9b508a0] KVM: x86/mmu: Protect TDP MMU page table memory with RCU
git bisect good 7cca2d0b7e7d9f3cd740d41afdc00051c9b508a0
# first bad commit: [26128cb6c7e6731fe644c687af97733adfdb5ee9] locking/rwlocks: Add contention detection for rwlocks