From cadae3a45d23aa4f6485938a67cbc47aaaa25e38 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Mon, 19 Aug 2024 22:24:01 +1000 Subject: 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 Reviewed-by: Nysal Jan K.A Reviewed-by: Kajol Jain Signed-off-by: Michael Ellerman Link: https://patch.msgid.link/20240819122401.513203-1-mpe@ellerman.id.au --- arch/powerpc/include/asm/dtl.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/powerpc/include/asm') 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 #include -#include /* * 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); -- cgit v1.3.1