Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 2fed7f8e authored by Liu Zixian's avatar Liu Zixian Committed by Greg Kroah-Hartman
Browse files

mm/hugetlb: initialize hugetlb_usage in mm_init 

commit 13db8c50477d83ad3e3b9b0ae247e5cd833a7ae4 upstream.

After fork, the child process will get incorrect (2x) hugetlb_usage.  If
a process uses 5 2MB hugetlb pages in an anonymous mapping,

	HugetlbPages:	   10240 kB

and then forks, the child will show,

	HugetlbPages:	   20480 kB

The reason for double the amount is because hugetlb_usage will be copied
from the parent and then increased when we copy page tables from parent
to child.  Child will have 2x actual usage.

Fix this by adding hugetlb_count_init in mm_init.

Link: https://lkml.kernel.org/r/20210826071742.877-1-liuzixian4@huawei.com


Fixes: 5d317b2b ("mm: hugetlb: proc: add HugetlbPages field to /proc/PID/status")
Signed-off-by: default avatarLiu Zixian <liuzixian4@huawei.com>
Reviewed-by: default avatarNaoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: default avatarMike Kravetz <mike.kravetz@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent cca7b5d2

include/linux/hugetlb.h

+9 −0
Original line number Original line Diff line number Diff line
@@ -513,6 +513,11 @@ static inline spinlock_t *huge_pte_lockptr(struct hstate *h, 




void hugetlb_report_usage(struct seq_file *m, struct mm_struct *mm);

void hugetlb_report_usage(struct seq_file *m, struct mm_struct *mm);





static inline void hugetlb_count_init(struct mm_struct *mm)

{

	atomic_long_set(&mm->hugetlb_usage, 0);

}



static inline void hugetlb_count_add(long l, struct mm_struct *mm)

static inline void hugetlb_count_add(long l, struct mm_struct *mm)

{

{

	atomic_long_add(l, &mm->hugetlb_usage);

	atomic_long_add(l, &mm->hugetlb_usage);
@@ -593,6 +598,10 @@ static inline spinlock_t *huge_pte_lockptr(struct hstate *h, 
	return &mm->page_table_lock;

	return &mm->page_table_lock;

}

}





static inline void hugetlb_count_init(struct mm_struct *mm)

{

}



static inline void hugetlb_report_usage(struct seq_file *f, struct mm_struct *m)

static inline void hugetlb_report_usage(struct seq_file *f, struct mm_struct *m)

{

{

}

}

kernel/fork.c

+1 −0
Original line number Original line Diff line number Diff line
@@ -964,6 +964,7 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p, 
	mm->pmd_huge_pte = NULL;

	mm->pmd_huge_pte = NULL;

#endif

#endif

	mm_init_uprobes_state(mm);

	mm_init_uprobes_state(mm);

	hugetlb_count_init(mm);





	if (current->mm) {

	if (current->mm) {

		mm->flags = current->mm->flags & MMF_INIT_MASK;

		mm->flags = current->mm->flags & MMF_INIT_MASK;