2023-09-19 20:54:56

by Stefan Roesch

Subject: [PATCH v1 1/2] mm/ksm: support fork/exec for prctl

A process can enable KSM with the prctl system call. When the process is
forked the KSM flag is inherited by the child process. However if the
process is executing an exec system call directly after the fork, the
KSM setting is cleared. This patch addresses this problem.

Signed-off-by: Stefan Roesch <[email protected]>
Reported-by: Carl Klemm <[email protected]>
---
include/linux/sched/coredump.h | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/include/linux/sched/coredump.h b/include/linux/sched/coredump.h
index 0ee96ea7a0e9..205aa9917394 100644
--- a/include/linux/sched/coredump.h
+++ b/include/linux/sched/coredump.h
@@ -87,8 +87,11 @@ static inline int get_dumpable(struct mm_struct *mm)

#define MMF_DISABLE_THP_MASK (1 << MMF_DISABLE_THP)

+#define MMF_VM_MERGE_ANY 29
+#define MMF_VM_MERGE_ANY_MASK (1 << MMF_VM_MERGE_ANY)
+
#define MMF_INIT_MASK (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK |\
- MMF_DISABLE_THP_MASK | MMF_HAS_MDWE_MASK)
+ MMF_DISABLE_THP_MASK | MMF_HAS_MDWE_MASK |\
+ MMF_VM_MERGE_ANY_MASK)

-#define MMF_VM_MERGE_ANY 29
#endif /* _LINUX_SCHED_COREDUMP_H */
--
2.39.3

2023-09-20 11:10:35

by Carl Klemm

Subject: Re: [PATCH v1 1/2] mm/ksm: support fork/exec for prctl

On Tue, 2023-09-19 at 13:51 -0700, Stefan Roesch wrote:
> A process can enable KSM with the prctl system call. When the process
> is
> forked the KSM flag is inherited by the child process. However if the
> process is executing an exec system call directly after the fork, the
> KSM setting is cleared. This patch addresses this problem.
>
> Signed-off-by: Stefan Roesch <[email protected]>
> Reported-by: Carl Klemm <[email protected]>
> ---
>  include/linux/sched/coredump.h | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/sched/coredump.h
> b/include/linux/sched/coredump.h
> index 0ee96ea7a0e9..205aa9917394 100644
> --- a/include/linux/sched/coredump.h
> +++ b/include/linux/sched/coredump.h
> @@ -87,8 +87,11 @@ static inline int get_dumpable(struct mm_struct
> *mm)
>  
>  #define MMF_DISABLE_THP_MASK   (1 << MMF_DISABLE_THP)
>  
> +#define MMF_VM_MERGE_ANY       29
> +#define MMF_VM_MERGE_ANY_MASK  (1 << MMF_VM_MERGE_ANY)
> +
>  #define MMF_INIT_MASK          (MMF_DUMPABLE_MASK |
> MMF_DUMP_FILTER_MASK |\
> -                                MMF_DISABLE_THP_MASK |
> MMF_HAS_MDWE_MASK)
> +                                MMF_DISABLE_THP_MASK |
> MMF_HAS_MDWE_MASK |\
> +                                MMF_VM_MERGE_ANY_MASK)
>  
> -#define MMF_VM_MERGE_ANY       29
>  #endif /* _LINUX_SCHED_COREDUMP_H */

I can confirm that this patch works as intended for my usecase, you can
have my:

Tested-by: Carl Klemm <[email protected]>

2023-09-20 17:55:10

by Stefan Roesch

Subject: Re: [PATCH v1 1/2] mm/ksm: support fork/exec for prctl

David Hildenbrand <[email protected]> writes:

> On 19.09.23 22:51, Stefan Roesch wrote:
>> A process can enable KSM with the prctl system call. When the process is
>> forked the KSM flag is inherited by the child process. However if the
>> process is executing an exec system call directly after the fork, the
>> KSM setting is cleared. This patch addresses this problem.
>> Signed-off-by: Stefan Roesch <[email protected]>
>> Reported-by: Carl Klemm <[email protected]>
>> ---
>> include/linux/sched/coredump.h | 7 +++++--
>> 1 file changed, 5 insertions(+), 2 deletions(-)
>> diff --git a/include/linux/sched/coredump.h b/include/linux/sched/coredump.h
>> index 0ee96ea7a0e9..205aa9917394 100644
>> --- a/include/linux/sched/coredump.h
>> +++ b/include/linux/sched/coredump.h
>> @@ -87,8 +87,11 @@ static inline int get_dumpable(struct mm_struct *mm)
>> #define MMF_DISABLE_THP_MASK (1 << MMF_DISABLE_THP)
>> +#define MMF_VM_MERGE_ANY 29
>> +#define MMF_VM_MERGE_ANY_MASK (1 << MMF_VM_MERGE_ANY)
>> +
>> #define MMF_INIT_MASK (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK |\
>> - MMF_DISABLE_THP_MASK | MMF_HAS_MDWE_MASK)
>> + MMF_DISABLE_THP_MASK | MMF_HAS_MDWE_MASK |\
>> + MMF_VM_MERGE_ANY_MASK)
>> -#define MMF_VM_MERGE_ANY 29
>> #endif /* _LINUX_SCHED_COREDUMP_H */
>
> Fixes: tag?
>

Added fixes tag

> Reviewed-by: David Hildenbrand <[email protected]>

2023-09-20 22:08:11

by David Hildenbrand

Subject: Re: [PATCH v1 1/2] mm/ksm: support fork/exec for prctl

On 19.09.23 22:51, Stefan Roesch wrote:
> A process can enable KSM with the prctl system call. When the process is
> forked the KSM flag is inherited by the child process. However if the
> process is executing an exec system call directly after the fork, the
> KSM setting is cleared. This patch addresses this problem.
>
> Signed-off-by: Stefan Roesch <[email protected]>
> Reported-by: Carl Klemm <[email protected]>
> ---
> include/linux/sched/coredump.h | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/sched/coredump.h b/include/linux/sched/coredump.h
> index 0ee96ea7a0e9..205aa9917394 100644
> --- a/include/linux/sched/coredump.h
> +++ b/include/linux/sched/coredump.h
> @@ -87,8 +87,11 @@ static inline int get_dumpable(struct mm_struct *mm)
>
> #define MMF_DISABLE_THP_MASK (1 << MMF_DISABLE_THP)
>
> +#define MMF_VM_MERGE_ANY 29
> +#define MMF_VM_MERGE_ANY_MASK (1 << MMF_VM_MERGE_ANY)
> +
> #define MMF_INIT_MASK (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK |\
> - MMF_DISABLE_THP_MASK | MMF_HAS_MDWE_MASK)
> + MMF_DISABLE_THP_MASK | MMF_HAS_MDWE_MASK |\
> + MMF_VM_MERGE_ANY_MASK)
>
> -#define MMF_VM_MERGE_ANY 29
> #endif /* _LINUX_SCHED_COREDUMP_H */

Fixes: tag?

Reviewed-by: David Hildenbrand <[email protected]>

--
Cheers,

David / dhildenb