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| author | Michael Ellerman <mpe@ellerman.id.au> | 2024-08-19 22:24:01 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2024-10-29 23:01:36 +1100 |
| commit | cadae3a45d23aa4f6485938a67cbc47aaaa25e38 (patch) | |
| tree | 518b83d729d01f597ce617c027f2abda9ba6b385 /arch/powerpc/include | |
| parent | b23b9edf64b6387334aa2f8687cca6792b0d9d6c (diff) | |
| download | lwn-cadae3a45d23aa4f6485938a67cbc47aaaa25e38.tar.gz lwn-cadae3a45d23aa4f6485938a67cbc47aaaa25e38.zip | |
powerpc/pseries: Fix dtl_access_lock to be a rw_semaphore
The dtl_access_lock needs to be a rw_sempahore, a sleeping lock, because
the code calls kmalloc() while holding it, which can sleep:
# echo 1 > /proc/powerpc/vcpudispatch_stats
BUG: sleeping function called from invalid context at include/linux/sched/mm.h:337
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 199, name: sh
preempt_count: 1, expected: 0
3 locks held by sh/199:
#0: c00000000a0743f8 (sb_writers#3){.+.+}-{0:0}, at: vfs_write+0x324/0x438
#1: c0000000028c7058 (dtl_enable_mutex){+.+.}-{3:3}, at: vcpudispatch_stats_write+0xd4/0x5f4
#2: c0000000028c70b8 (dtl_access_lock){+.+.}-{2:2}, at: vcpudispatch_stats_write+0x220/0x5f4
CPU: 0 PID: 199 Comm: sh Not tainted 6.10.0-rc4 #152
Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1202 0xf000005 of:SLOF,HEAD hv:linux,kvm pSeries
Call Trace:
dump_stack_lvl+0x130/0x148 (unreliable)
__might_resched+0x174/0x410
kmem_cache_alloc_noprof+0x340/0x3d0
alloc_dtl_buffers+0x124/0x1ac
vcpudispatch_stats_write+0x2a8/0x5f4
proc_reg_write+0xf4/0x150
vfs_write+0xfc/0x438
ksys_write+0x88/0x148
system_call_exception+0x1c4/0x5a0
system_call_common+0xf4/0x258
Fixes: 06220d78f24a ("powerpc/pseries: Introduce rwlock to gatekeep DTLB usage")
Tested-by: Kajol Jain <kjain@linux.ibm.com>
Reviewed-by: Nysal Jan K.A <nysal@linux.ibm.com>
Reviewed-by: Kajol Jain <kjain@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://patch.msgid.link/20240819122401.513203-1-mpe@ellerman.id.au
Diffstat (limited to 'arch/powerpc/include')
| -rw-r--r-- | arch/powerpc/include/asm/dtl.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/powerpc/include/asm/dtl.h b/arch/powerpc/include/asm/dtl.h index d6f43d149f8d..a5c21bc623cb 100644 --- a/arch/powerpc/include/asm/dtl.h +++ b/arch/powerpc/include/asm/dtl.h @@ -1,8 +1,8 @@ #ifndef _ASM_POWERPC_DTL_H #define _ASM_POWERPC_DTL_H +#include <linux/rwsem.h> #include <asm/lppaca.h> -#include <linux/spinlock_types.h> /* * Layout of entries in the hypervisor's dispatch trace log buffer. @@ -35,7 +35,7 @@ struct dtl_entry { #define DTL_LOG_ALL (DTL_LOG_CEDE | DTL_LOG_PREEMPT | DTL_LOG_FAULT) extern struct kmem_cache *dtl_cache; -extern rwlock_t dtl_access_lock; +extern struct rw_semaphore dtl_access_lock; extern void register_dtl_buffer(int cpu); extern void alloc_dtl_buffers(unsigned long *time_limit); |