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

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Message-ID: <qvqwmsxgbyg5.fsf@devbig1114.prn1.facebook.com>
Date:   Wed, 20 Sep 2023 09:29:00 -0700
From:   Stefan Roesch <shr@...kernel.io>
To:     David Hildenbrand <david@...hat.com>
Cc:     kernel-team@...com, akpm@...ux-foundation.org, hannes@...xchg.org,
        riel@...riel.com, linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Carl Klemm <carl@...s.xyz>
Subject: Re: [PATCH v1 1/2] mm/ksm: support fork/exec for prctl


David Hildenbrand <david@...hat.com> 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 <shr@...kernel.io>
>> Reported-by: Carl Klemm <carl@...s.xyz>
>> ---
>>   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 <david@...hat.com>