Re: [PATCH v2] powerpc/lockdep: fix a false positive warning
* Qian Cai wrote: > I thought about making it a bool in the first place, but since all > other similar helpers (arch_is_kernel_initmem_freed(), > arch_is_kernel_text(), arch_is_kernel_data() etc) could be bool too but > are not, I kept arch_is_bss_hole() just to be “int” for consistent. > > Although then there is is_kernel_rodata() which is bool. I suppose I’ll > change arch_is_bss_hole() to bool, and then could have a follow-up > patch to covert all similar helpers to return boo instead. Sounds good to me. Thanks, Ingo
Re: [PATCH v2] powerpc/lockdep: fix a false positive warning
> On Sep 7, 2019, at 3:05 AM, Ingo Molnar wrote:
>
>
> * Qian Cai wrote:
>
>> The commit 108c14858b9e ("locking/lockdep: Add support for dynamic
>> keys") introduced a boot warning on powerpc below, because since the
>> commit 2d4f567103ff ("KVM: PPC: Introduce kvm_tmp framework") adds
>> kvm_tmp[] into the .bss section and then free the rest of unused spaces
>> back to the page allocator.
>>
>> kernel_init
>> kvm_guest_init
>>kvm_free_tmp
>> free_reserved_area
>>free_unref_page
>> free_unref_page_prepare
>>
>> Later, alloc_workqueue() happens to allocate some pages from there and
>> trigger the warning at,
>>
>> if (WARN_ON_ONCE(static_obj(key)))
>>
>> Fix it by adding a generic helper arch_is_bss_hole() to skip those areas
>> in static_obj(). Since kvm_free_tmp() is only done early during the
>> boot, just go lockless to make the implementation simple for now.
>>
>> WARNING: CPU: 0 PID: 13 at kernel/locking/lockdep.c:1120
>> Workqueue: events work_for_cpu_fn
>> Call Trace:
>> lockdep_register_key+0x68/0x200
>> wq_init_lockdep+0x40/0xc0
>> trunc_msg+0x385f9/0x4c30f (unreliable)
>> wq_init_lockdep+0x40/0xc0
>> alloc_workqueue+0x1e0/0x620
>> scsi_host_alloc+0x3d8/0x490
>> ata_scsi_add_hosts+0xd0/0x220 [libata]
>> ata_host_register+0x178/0x400 [libata]
>> ata_host_activate+0x17c/0x210 [libata]
>> ahci_host_activate+0x84/0x250 [libahci]
>> ahci_init_one+0xc74/0xdc0 [ahci]
>> local_pci_probe+0x78/0x100
>> work_for_cpu_fn+0x40/0x70
>> process_one_work+0x388/0x750
>> process_scheduled_works+0x50/0x90
>> worker_thread+0x3d0/0x570
>> kthread+0x1b8/0x1e0
>> ret_from_kernel_thread+0x5c/0x7c
>>
>> Fixes: 108c14858b9e ("locking/lockdep: Add support for dynamic keys")
>> Signed-off-by: Qian Cai
>> ---
>>
>> v2: No need to actually define arch_is_bss_hole() powerpc64 only.
>>
>> arch/powerpc/include/asm/sections.h | 11 +++
>> arch/powerpc/kernel/kvm.c | 5 +
>> include/asm-generic/sections.h | 7 +++
>> kernel/locking/lockdep.c| 3 +++
>> 4 files changed, 26 insertions(+)
>>
>> diff --git a/arch/powerpc/include/asm/sections.h
>> b/arch/powerpc/include/asm/sections.h
>> index 4a1664a8658d..4f5d69c42017 100644
>> --- a/arch/powerpc/include/asm/sections.h
>> +++ b/arch/powerpc/include/asm/sections.h
>> @@ -5,8 +5,19 @@
>>
>> #include
>> #include
>> +
>> +#define arch_is_bss_hole arch_is_bss_hole
>> +
>> #include
>>
>> +extern void *bss_hole_start, *bss_hole_end;
>> +
>> +static inline int arch_is_bss_hole(unsigned long addr)
>> +{
>> +return addr >= (unsigned long)bss_hole_start &&
>> + addr < (unsigned long)bss_hole_end;
>> +}
>> +
>> extern char __head_end[];
>>
>> #ifdef __powerpc64__
>> diff --git a/arch/powerpc/kernel/kvm.c b/arch/powerpc/kernel/kvm.c
>> index b7b3a5e4e224..89e0e522e125 100644
>> --- a/arch/powerpc/kernel/kvm.c
>> +++ b/arch/powerpc/kernel/kvm.c
>> @@ -66,6 +66,7 @@
>> static bool kvm_patching_worked = true;
>> char kvm_tmp[1024 * 1024];
>> static int kvm_tmp_index;
>> +void *bss_hole_start, *bss_hole_end;
>>
>> static inline void kvm_patch_ins(u32 *inst, u32 new_inst)
>> {
>> @@ -707,6 +708,10 @@ static __init void kvm_free_tmp(void)
>> */
>> kmemleak_free_part(_tmp[kvm_tmp_index],
>> ARRAY_SIZE(kvm_tmp) - kvm_tmp_index);
>> +
>> +bss_hole_start = _tmp[kvm_tmp_index];
>> +bss_hole_end = _tmp[ARRAY_SIZE(kvm_tmp)];
>> +
>> free_reserved_area(_tmp[kvm_tmp_index],
>> _tmp[ARRAY_SIZE(kvm_tmp)], -1, NULL);
>> }
>> diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
>> index d1779d442aa5..4d8b1f2c5fd9 100644
>> --- a/include/asm-generic/sections.h
>> +++ b/include/asm-generic/sections.h
>> @@ -91,6 +91,13 @@ static inline int arch_is_kernel_initmem_freed(unsigned
>> long addr)
>> }
>> #endif
>>
>> +#ifndef arch_is_bss_hole
>> +static inline int arch_is_bss_hole(unsigned long addr)
>> +{
>> +return 0;
>> +}
>> +#endif
>> +
>> /**
>> * memory_contains - checks if an object is contained within a memory region
>> * @begin: virtual address of the beginning of the memory region
>> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
>> index 4861cf8e274b..cd75b51f15ce 100644
>> --- a/kernel/locking/lockdep.c
>> +++ b/kernel/locking/lockdep.c
>> @@ -675,6 +675,9 @@ static int static_obj(const void *obj)
>> if (arch_is_kernel_initmem_freed(addr))
>> return 0;
>>
>> +if (arch_is_bss_hole(addr))
>> +return 0;
>
> arch_is_bss_hole() should use a 'bool' - but other than that, this
> looks good to me, if the PowerPC maintainers agree too.
I thought about making it a bool in the first place, but since all other
similar helpers
(arch_is_kernel_initmem_freed(), arch_is_kernel_text(), arch_is_kernel_data()
etc)
could be bool too but are not, I kept arch_is_bss_hole() just to be “int” for
consistent.
Although then there is is_kernel_rodata()
Re: [PATCH v2] powerpc/lockdep: fix a false positive warning
* Qian Cai wrote:
> The commit 108c14858b9e ("locking/lockdep: Add support for dynamic
> keys") introduced a boot warning on powerpc below, because since the
> commit 2d4f567103ff ("KVM: PPC: Introduce kvm_tmp framework") adds
> kvm_tmp[] into the .bss section and then free the rest of unused spaces
> back to the page allocator.
>
> kernel_init
> kvm_guest_init
> kvm_free_tmp
> free_reserved_area
> free_unref_page
> free_unref_page_prepare
>
> Later, alloc_workqueue() happens to allocate some pages from there and
> trigger the warning at,
>
> if (WARN_ON_ONCE(static_obj(key)))
>
> Fix it by adding a generic helper arch_is_bss_hole() to skip those areas
> in static_obj(). Since kvm_free_tmp() is only done early during the
> boot, just go lockless to make the implementation simple for now.
>
> WARNING: CPU: 0 PID: 13 at kernel/locking/lockdep.c:1120
> Workqueue: events work_for_cpu_fn
> Call Trace:
> lockdep_register_key+0x68/0x200
> wq_init_lockdep+0x40/0xc0
> trunc_msg+0x385f9/0x4c30f (unreliable)
> wq_init_lockdep+0x40/0xc0
> alloc_workqueue+0x1e0/0x620
> scsi_host_alloc+0x3d8/0x490
> ata_scsi_add_hosts+0xd0/0x220 [libata]
> ata_host_register+0x178/0x400 [libata]
> ata_host_activate+0x17c/0x210 [libata]
> ahci_host_activate+0x84/0x250 [libahci]
> ahci_init_one+0xc74/0xdc0 [ahci]
> local_pci_probe+0x78/0x100
> work_for_cpu_fn+0x40/0x70
> process_one_work+0x388/0x750
> process_scheduled_works+0x50/0x90
> worker_thread+0x3d0/0x570
> kthread+0x1b8/0x1e0
> ret_from_kernel_thread+0x5c/0x7c
>
> Fixes: 108c14858b9e ("locking/lockdep: Add support for dynamic keys")
> Signed-off-by: Qian Cai
> ---
>
> v2: No need to actually define arch_is_bss_hole() powerpc64 only.
>
> arch/powerpc/include/asm/sections.h | 11 +++
> arch/powerpc/kernel/kvm.c | 5 +
> include/asm-generic/sections.h | 7 +++
> kernel/locking/lockdep.c| 3 +++
> 4 files changed, 26 insertions(+)
>
> diff --git a/arch/powerpc/include/asm/sections.h
> b/arch/powerpc/include/asm/sections.h
> index 4a1664a8658d..4f5d69c42017 100644
> --- a/arch/powerpc/include/asm/sections.h
> +++ b/arch/powerpc/include/asm/sections.h
> @@ -5,8 +5,19 @@
>
> #include
> #include
> +
> +#define arch_is_bss_hole arch_is_bss_hole
> +
> #include
>
> +extern void *bss_hole_start, *bss_hole_end;
> +
> +static inline int arch_is_bss_hole(unsigned long addr)
> +{
> + return addr >= (unsigned long)bss_hole_start &&
> +addr < (unsigned long)bss_hole_end;
> +}
> +
> extern char __head_end[];
>
> #ifdef __powerpc64__
> diff --git a/arch/powerpc/kernel/kvm.c b/arch/powerpc/kernel/kvm.c
> index b7b3a5e4e224..89e0e522e125 100644
> --- a/arch/powerpc/kernel/kvm.c
> +++ b/arch/powerpc/kernel/kvm.c
> @@ -66,6 +66,7 @@
> static bool kvm_patching_worked = true;
> char kvm_tmp[1024 * 1024];
> static int kvm_tmp_index;
> +void *bss_hole_start, *bss_hole_end;
>
> static inline void kvm_patch_ins(u32 *inst, u32 new_inst)
> {
> @@ -707,6 +708,10 @@ static __init void kvm_free_tmp(void)
>*/
> kmemleak_free_part(_tmp[kvm_tmp_index],
> ARRAY_SIZE(kvm_tmp) - kvm_tmp_index);
> +
> + bss_hole_start = _tmp[kvm_tmp_index];
> + bss_hole_end = _tmp[ARRAY_SIZE(kvm_tmp)];
> +
> free_reserved_area(_tmp[kvm_tmp_index],
> _tmp[ARRAY_SIZE(kvm_tmp)], -1, NULL);
> }
> diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
> index d1779d442aa5..4d8b1f2c5fd9 100644
> --- a/include/asm-generic/sections.h
> +++ b/include/asm-generic/sections.h
> @@ -91,6 +91,13 @@ static inline int arch_is_kernel_initmem_freed(unsigned
> long addr)
> }
> #endif
>
> +#ifndef arch_is_bss_hole
> +static inline int arch_is_bss_hole(unsigned long addr)
> +{
> + return 0;
> +}
> +#endif
> +
> /**
> * memory_contains - checks if an object is contained within a memory region
> * @begin: virtual address of the beginning of the memory region
> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
> index 4861cf8e274b..cd75b51f15ce 100644
> --- a/kernel/locking/lockdep.c
> +++ b/kernel/locking/lockdep.c
> @@ -675,6 +675,9 @@ static int static_obj(const void *obj)
> if (arch_is_kernel_initmem_freed(addr))
> return 0;
>
> + if (arch_is_bss_hole(addr))
> + return 0;
arch_is_bss_hole() should use a 'bool' - but other than that, this
looks good to me, if the PowerPC maintainers agree too.
Thanks,
Ingo
[PATCH v2] powerpc/lockdep: fix a false positive warning
The commit 108c14858b9e ("locking/lockdep: Add support for dynamic
keys") introduced a boot warning on powerpc below, because since the
commit 2d4f567103ff ("KVM: PPC: Introduce kvm_tmp framework") adds
kvm_tmp[] into the .bss section and then free the rest of unused spaces
back to the page allocator.
kernel_init
kvm_guest_init
kvm_free_tmp
free_reserved_area
free_unref_page
free_unref_page_prepare
Later, alloc_workqueue() happens to allocate some pages from there and
trigger the warning at,
if (WARN_ON_ONCE(static_obj(key)))
Fix it by adding a generic helper arch_is_bss_hole() to skip those areas
in static_obj(). Since kvm_free_tmp() is only done early during the
boot, just go lockless to make the implementation simple for now.
WARNING: CPU: 0 PID: 13 at kernel/locking/lockdep.c:1120
Workqueue: events work_for_cpu_fn
Call Trace:
lockdep_register_key+0x68/0x200
wq_init_lockdep+0x40/0xc0
trunc_msg+0x385f9/0x4c30f (unreliable)
wq_init_lockdep+0x40/0xc0
alloc_workqueue+0x1e0/0x620
scsi_host_alloc+0x3d8/0x490
ata_scsi_add_hosts+0xd0/0x220 [libata]
ata_host_register+0x178/0x400 [libata]
ata_host_activate+0x17c/0x210 [libata]
ahci_host_activate+0x84/0x250 [libahci]
ahci_init_one+0xc74/0xdc0 [ahci]
local_pci_probe+0x78/0x100
work_for_cpu_fn+0x40/0x70
process_one_work+0x388/0x750
process_scheduled_works+0x50/0x90
worker_thread+0x3d0/0x570
kthread+0x1b8/0x1e0
ret_from_kernel_thread+0x5c/0x7c
Fixes: 108c14858b9e ("locking/lockdep: Add support for dynamic keys")
Signed-off-by: Qian Cai
---
v2: No need to actually define arch_is_bss_hole() powerpc64 only.
arch/powerpc/include/asm/sections.h | 11 +++
arch/powerpc/kernel/kvm.c | 5 +
include/asm-generic/sections.h | 7 +++
kernel/locking/lockdep.c| 3 +++
4 files changed, 26 insertions(+)
diff --git a/arch/powerpc/include/asm/sections.h
b/arch/powerpc/include/asm/sections.h
index 4a1664a8658d..4f5d69c42017 100644
--- a/arch/powerpc/include/asm/sections.h
+++ b/arch/powerpc/include/asm/sections.h
@@ -5,8 +5,19 @@
#include
#include
+
+#define arch_is_bss_hole arch_is_bss_hole
+
#include
+extern void *bss_hole_start, *bss_hole_end;
+
+static inline int arch_is_bss_hole(unsigned long addr)
+{
+ return addr >= (unsigned long)bss_hole_start &&
+ addr < (unsigned long)bss_hole_end;
+}
+
extern char __head_end[];
#ifdef __powerpc64__
diff --git a/arch/powerpc/kernel/kvm.c b/arch/powerpc/kernel/kvm.c
index b7b3a5e4e224..89e0e522e125 100644
--- a/arch/powerpc/kernel/kvm.c
+++ b/arch/powerpc/kernel/kvm.c
@@ -66,6 +66,7 @@
static bool kvm_patching_worked = true;
char kvm_tmp[1024 * 1024];
static int kvm_tmp_index;
+void *bss_hole_start, *bss_hole_end;
static inline void kvm_patch_ins(u32 *inst, u32 new_inst)
{
@@ -707,6 +708,10 @@ static __init void kvm_free_tmp(void)
*/
kmemleak_free_part(_tmp[kvm_tmp_index],
ARRAY_SIZE(kvm_tmp) - kvm_tmp_index);
+
+ bss_hole_start = _tmp[kvm_tmp_index];
+ bss_hole_end = _tmp[ARRAY_SIZE(kvm_tmp)];
+
free_reserved_area(_tmp[kvm_tmp_index],
_tmp[ARRAY_SIZE(kvm_tmp)], -1, NULL);
}
diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
index d1779d442aa5..4d8b1f2c5fd9 100644
--- a/include/asm-generic/sections.h
+++ b/include/asm-generic/sections.h
@@ -91,6 +91,13 @@ static inline int arch_is_kernel_initmem_freed(unsigned long
addr)
}
#endif
+#ifndef arch_is_bss_hole
+static inline int arch_is_bss_hole(unsigned long addr)
+{
+ return 0;
+}
+#endif
+
/**
* memory_contains - checks if an object is contained within a memory region
* @begin: virtual address of the beginning of the memory region
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 4861cf8e274b..cd75b51f15ce 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -675,6 +675,9 @@ static int static_obj(const void *obj)
if (arch_is_kernel_initmem_freed(addr))
return 0;
+ if (arch_is_bss_hole(addr))
+ return 0;
+
/*
* static variable?
*/
--
2.20.1 (Apple Git-117)
