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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Thu, 1 Aug 2019 04:33:29 +0100 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x713XSVw61472966 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 1 Aug 2019 03:33:28 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5E6C611C04C; Thu, 1 Aug 2019 03:33:28 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B98FE11C04A; Thu, 1 Aug 2019 03:33:27 +0000 (GMT) Received: from ozlabs.au.ibm.com (unknown [9.192.253.14]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 1 Aug 2019 03:33:27 +0000 (GMT) Received: from [10.61.2.125] (haven.au.ibm.com [9.192.254.114]) (using TLSv1.2 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by ozlabs.au.ibm.com (Postfix) with ESMTPSA id 84C4FA01FE; Thu, 1 Aug 2019 13:33:25 +1000 (AEST) Subject: Re: [PATCH 3/3] powerpc/spinlock: Fix oops in shared-processor spinlocks To: "Christopher M. Riedl" , linuxppc-dev@ozlabs.org References: <20190728125438.1550-1-cmr@informatik.wtf> <20190728125438.1550-4-cmr@informatik.wtf> From: Andrew Donnellan Date: Thu, 1 Aug 2019 13:33:25 +1000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190728125438.1550-4-cmr@informatik.wtf> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-AU Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 19080103-0012-0000-0000-000003383841 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19080103-0013-0000-0000-00002171E36D Message-Id: <750b390e-678d-0b26-d004-f05f1dcd52fb@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-08-01_02:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1908010029 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 28/7/19 10:54 pm, Christopher M. Riedl wrote: > Booting w/ ppc64le_defconfig + CONFIG_PREEMPT results in the attached > kernel trace due to calling shared-processor spinlocks while not running > in an SPLPAR. Previously, the out-of-line spinlocks implementations were > selected based on CONFIG_PPC_SPLPAR at compile time without a runtime > shared-processor LPAR check. > > To fix, call the actual spinlock implementations from a set of common > functions, spin_yield() and rw_yield(), which check for shared-processor > LPAR during runtime and select the appropriate lock implementation. > > [ 0.430878] BUG: Kernel NULL pointer dereference at 0x00000100 > [ 0.431991] Faulting instruction address: 0xc000000000097f88 > [ 0.432934] Oops: Kernel access of bad area, sig: 7 [#1] > [ 0.433448] LE PAGE_SIZE=64K MMU=Radix MMU=Hash PREEMPT SMP NR_CPUS=2048 NUMA PowerNV > [ 0.434479] Modules linked in: > [ 0.435055] CPU: 0 PID: 2 Comm: kthreadd Not tainted 5.2.0-rc6-00491-g249155c20f9b #28 > [ 0.435730] NIP: c000000000097f88 LR: c000000000c07a88 CTR: c00000000015ca10 > [ 0.436383] REGS: c0000000727079f0 TRAP: 0300 Not tainted (5.2.0-rc6-00491-g249155c20f9b) > [ 0.437004] MSR: 9000000002009033 CR: 84000424 XER: 20040000 > [ 0.437874] CFAR: c000000000c07a84 DAR: 0000000000000100 DSISR: 00080000 IRQMASK: 1 > [ 0.437874] GPR00: c000000000c07a88 c000000072707c80 c000000001546300 c00000007be38a80 > [ 0.437874] GPR04: c0000000726f0c00 0000000000000002 c00000007279c980 0000000000000100 > [ 0.437874] GPR08: c000000001581b78 0000000080000001 0000000000000008 c00000007279c9b0 > [ 0.437874] GPR12: 0000000000000000 c000000001730000 c000000000142558 0000000000000000 > [ 0.437874] GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > [ 0.437874] GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > [ 0.437874] GPR24: c00000007be38a80 c000000000c002f4 0000000000000000 0000000000000000 > [ 0.437874] GPR28: c000000072221a00 c0000000726c2600 c00000007be38a80 c00000007be38a80 > [ 0.443992] NIP [c000000000097f88] __spin_yield+0x48/0xa0 > [ 0.444523] LR [c000000000c07a88] __raw_spin_lock+0xb8/0xc0 > [ 0.445080] Call Trace: > [ 0.445670] [c000000072707c80] [c000000072221a00] 0xc000000072221a00 (unreliable) > [ 0.446425] [c000000072707cb0] [c000000000bffb0c] __schedule+0xbc/0x850 > [ 0.447078] [c000000072707d70] [c000000000c002f4] schedule+0x54/0x130 > [ 0.447694] [c000000072707da0] [c0000000001427dc] kthreadd+0x28c/0x2b0 > [ 0.448389] [c000000072707e20] [c00000000000c1cc] ret_from_kernel_thread+0x5c/0x70 > [ 0.449143] Instruction dump: > [ 0.449821] 4d9e0020 552a043e 210a07ff 79080fe0 0b080000 3d020004 3908b878 794a1f24 > [ 0.450587] e8e80000 7ce7502a e8e70000 38e70100 <7ca03c2c> 70a70001 78a50020 4d820020 > [ 0.452808] ---[ end trace 474d6b2b8fc5cb7e ]--- > > Signed-off-by: Christopher M. Riedl This should probably head to stable? > --- > arch/powerpc/include/asm/spinlock.h | 36 ++++++++++++++++++++--------- > 1 file changed, 25 insertions(+), 11 deletions(-) > > diff --git a/arch/powerpc/include/asm/spinlock.h b/arch/powerpc/include/asm/spinlock.h > index 1e7721176f39..8161809c6be1 100644 > --- a/arch/powerpc/include/asm/spinlock.h > +++ b/arch/powerpc/include/asm/spinlock.h > @@ -103,11 +103,9 @@ static inline int arch_spin_trylock(arch_spinlock_t *lock) > /* We only yield to the hypervisor if we are in shared processor mode */ > void splpar_spin_yield(arch_spinlock_t *lock); > void splpar_rw_yield(arch_rwlock_t *lock); > -#define __spin_yield(x) splpar_spin_yield(x) > -#define __rw_yield(x) splpar_rw_yield(x) > #else /* SPLPAR */ > -#define __spin_yield(x) barrier() > -#define __rw_yield(x) barrier() > +#define splpar_spin_yield(lock) > +#define splpar_rw_yield(lock) I prefer using #ifdef on the function definition and declaring an alternative function with an empty body for the !SPLPAR case, seeing an empty #define just feels a bit weird > #endif > > static inline bool is_shared_processor(void) > @@ -121,6 +119,22 @@ static inline bool is_shared_processor(void) > #endif > } > > +static inline void spin_yield(arch_spinlock_t *lock) > +{ > + if (is_shared_processor()) > + splpar_spin_yield(lock); > + else > + barrier(); > +} > + > +static inline void rw_yield(arch_rwlock_t *lock) > +{ > + if (is_shared_processor()) > + splpar_rw_yield(lock); > + else > + barrier(); > +} > + > static inline void arch_spin_lock(arch_spinlock_t *lock) > { > while (1) { > @@ -129,7 +143,7 @@ static inline void arch_spin_lock(arch_spinlock_t *lock) > do { > HMT_low(); > if (is_shared_processor()) > - __spin_yield(lock); > + spin_yield(lock); > } while (unlikely(lock->slock != 0)); > HMT_medium(); > } > @@ -148,7 +162,7 @@ void arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags) > do { > HMT_low(); > if (is_shared_processor()) > - __spin_yield(lock); > + spin_yield(lock); > } while (unlikely(lock->slock != 0)); > HMT_medium(); > local_irq_restore(flags_dis); > @@ -238,7 +252,7 @@ static inline void arch_read_lock(arch_rwlock_t *rw) > do { > HMT_low(); > if (is_shared_processor()) > - __rw_yield(rw); > + rw_yield(rw); > } while (unlikely(rw->lock < 0)); > HMT_medium(); > } > @@ -252,7 +266,7 @@ static inline void arch_write_lock(arch_rwlock_t *rw) > do { > HMT_low(); > if (is_shared_processor()) > - __rw_yield(rw); > + rw_yield(rw); > } while (unlikely(rw->lock != 0)); > HMT_medium(); > } > @@ -292,9 +306,9 @@ static inline void arch_write_unlock(arch_rwlock_t *rw) > rw->lock = 0; > } > > -#define arch_spin_relax(lock) __spin_yield(lock) > -#define arch_read_relax(lock) __rw_yield(lock) > -#define arch_write_relax(lock) __rw_yield(lock) > +#define arch_spin_relax(lock) spin_yield(lock) > +#define arch_read_relax(lock) rw_yield(lock) > +#define arch_write_relax(lock) rw_yield(lock) > > /* See include/linux/spinlock.h */ > #define smp_mb__after_spinlock() smp_mb() > -- Andrew Donnellan OzLabs, ADL Canberra ajd@linux.ibm.com IBM Australia Limited