Re: [PATCH v3] mm/ksm: fix ksm exec support for prctl

[Jinjiang Tu <tujinjiang@huawei.com>]

Sorry, the v3 tag is erroneous. This patch is the first version.

在 2024/3/18 17:04, Jinjiang Tu 写道:
> commit 3c6f33b7273a ("mm/ksm: support fork/exec for prctl") inherits
> MMF_VM_MERGE_ANY flag when a task calls execve(). Howerver, it doesn't
> create the mm_slot, so ksmd will not try to scan this task.
>
> To fix it, allocate and add the mm_slot to ksm_mm_head in __bprm_mm_init()
> when the mm has MMF_VM_MERGE_ANY flag.
>
> Fixes: 3c6f33b7273a ("mm/ksm: support fork/exec for prctl")
> Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com>
> ---
>   fs/exec.c           |  4 ++++
>   include/linux/ksm.h | 13 +++++++++++++
>   2 files changed, 17 insertions(+)
>
> diff --git a/fs/exec.c b/fs/exec.c
> index ff6f26671cfc..00f40163cc12 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -67,6 +67,7 @@
>   #include <linux/time_namespace.h>
>   #include <linux/user_events.h>
>   #include <linux/rseq.h>
> +#include <linux/ksm.h>
>   
>   #include <linux/uaccess.h>
>   #include <asm/mmu_context.h>
> @@ -267,6 +268,9 @@ static int __bprm_mm_init(struct linux_binprm *bprm)
>   		goto err_free;
>   	}
>   
> +	if (ksm_execve(mm))
> +		goto err;
> +
>   	/*
>   	 * Place the stack at the largest stack address the architecture
>   	 * supports. Later, we'll move this to an appropriate place. We don't
> diff --git a/include/linux/ksm.h b/include/linux/ksm.h
> index 401348e9f92b..7e2b1de3996a 100644
> --- a/include/linux/ksm.h
> +++ b/include/linux/ksm.h
> @@ -59,6 +59,14 @@ static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
>   	return 0;
>   }
>   
> +static inline int ksm_execve(struct mm_struct *mm)
> +{
> +	if (test_bit(MMF_VM_MERGE_ANY, &mm->flags))
> +		return __ksm_enter(mm);
> +
> +	return 0;
> +}
> +
>   static inline void ksm_exit(struct mm_struct *mm)
>   {
>   	if (test_bit(MMF_VM_MERGEABLE, &mm->flags))
> @@ -107,6 +115,11 @@ static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
>   	return 0;
>   }
>   
> +static inline int ksm_execve(struct mm_struct *mm)
> +{
> +	return 0;
> +}
> +
>   static inline void ksm_exit(struct mm_struct *mm)
>   {
>   }