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mm/hugetlb: initialize hugetlb_usage in mm_init
commit13db8c5047
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:5d317b2b65
("mm: hugetlb: proc: add HugetlbPages field to /proc/PID/status") Signed-off-by: Liu Zixian <liuzixian4@huawei.com> Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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2 changed files with 10 additions and 0 deletions
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@ -722,6 +722,11 @@ static inline spinlock_t *huge_pte_lockptr(struct hstate *h,
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void hugetlb_report_usage(struct seq_file *m, struct mm_struct *mm);
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static inline void hugetlb_count_init(struct mm_struct *mm)
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{
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atomic_long_set(&mm->hugetlb_usage, 0);
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}
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static inline void hugetlb_count_add(long l, struct mm_struct *mm)
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{
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atomic_long_add(l, &mm->hugetlb_usage);
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@ -897,6 +902,10 @@ static inline spinlock_t *huge_pte_lockptr(struct hstate *h,
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return &mm->page_table_lock;
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}
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static inline void hugetlb_count_init(struct mm_struct *mm)
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{
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}
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static inline void hugetlb_report_usage(struct seq_file *f, struct mm_struct *m)
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{
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}
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@ -1037,6 +1037,7 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
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mm->pmd_huge_pte = NULL;
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#endif
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mm_init_uprobes_state(mm);
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hugetlb_count_init(mm);
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if (current->mm) {
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mm->flags = current->mm->flags & MMF_INIT_MASK;
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