Re: [PATCH mm-unstable v19 05/14] mm/khugepaged: require collapse_huge_page to enter/exit with the lock dropped

[Zi Yan]

On 5 Jun 2026, at 12:14, Nico Pache wrote:

> Currently the collapse_huge_page function requires the mmap_read_lock to
> enter with it held, and exit with it dropped. This function moves the
> unlock into its parent caller, and changes this semantic to requiring it
> to enter/exit with it always unlocked.
>
> In future patches, we need this expectation, as for in mTHP collapse, we
> may have already dropped the lock, and do not want to conditionally
> check for this by passing through the lock_dropped variable.
>
> No functional change is expected as one of the first things the
> collapse_huge_page function does is drop this lock before allocating the
> hugepage.
>
> Reviewed-by: Lorenzo Stoakes <ljs@xxxxxxxxxx>
> Acked-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>
> Signed-off-by: Nico Pache <npache@xxxxxxxxxx>
> ---
>  mm/khugepaged.c | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
>
LGTM.

Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>

Best Regards,
Yan, Zi