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    SubjectRe: [RFC PATCH 08/15] fs: proc: use PAGES_PER_SECTION for page offline checking period.
    On Thu, Aug 05, 2021 at 03:02:46PM -0400, Zi Yan wrote:
    > From: Zi Yan <ziy@nvidia.com>
    >
    > It keeps the existing behavior after MAX_ORDER is increased beyond
    > a section size.
    >
    > Signed-off-by: Zi Yan <ziy@nvidia.com>
    > Cc: Mike Rapoport <rppt@kernel.org>
    > Cc: David Hildenbrand <david@redhat.com>
    > Cc: Oscar Salvador <osalvador@suse.de>
    > Cc: Ying Chen <chenying.kernel@bytedance.com>
    > Cc: Feng Zhou <zhoufeng.zf@bytedance.com>
    > Cc: linux-fsdevel@vger.kernel.org
    > Cc: linux-mm@kvack.org
    > Cc: linux-kernel@vger.kernel.org
    > ---
    > fs/proc/kcore.c | 2 +-
    > 1 file changed, 1 insertion(+), 1 deletion(-)
    >
    > diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
    > index 3f148759a5fd..77b7ba48fb44 100644
    > --- a/fs/proc/kcore.c
    > +++ b/fs/proc/kcore.c
    > @@ -486,7 +486,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
    > }
    > }
    >
    > - if (page_offline_frozen++ % MAX_ORDER_NR_PAGES == 0) {
    > + if (page_offline_frozen++ % PAGES_PER_SECTION == 0) {

    The behavior changes here. E.g. with default configuration on x86 instead
    of cond_resched() every 2M we get cond_resched() every 128M.

    I'm not saying it's wrong but at least it deserves an explanation why.

    > page_offline_thaw();
    > cond_resched();
    > page_offline_freeze();
    > --
    > 2.30.2
    >

    --
    Sincerely yours,
    Mike.

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