Re: [PATCH v20 13/20] mm/mlock: remove lru_lock on TestClearPageMlocked

[Johannes Weiner]

On Thu, Oct 29, 2020 at 06:44:58PM +0800, Alex Shi wrote:
> In the func munlock_vma_page, comments mentained lru_lock needed for
> serialization with split_huge_pages. But the page must be PageLocked
> as well as pages in split_huge_page series funcs. Thus the PageLocked
> is enough to serialize both funcs.
> 
> Further more, Hugh Dickins pointed: before splitting in
> split_huge_page_to_list, the page was unmap_page() to remove pmd/ptes
> which protect the page from munlock. Thus, no needs to guard
> __split_huge_page_tail for mlock clean, just keep the lru_lock there for
> isolation purpose.
> 
> LKP found a preempt issue on __mod_zone_page_state which need change
> to mod_zone_page_state. Thanks!
> 
> Signed-off-by: Alex Shi <alex.shi@xxxxxxxxxxxxxxxxx>
> Acked-by: Hugh Dickins <hughd@xxxxxxxxxx>
> Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> Cc: Vlastimil Babka <vbabka@xxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: linux-mm@xxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx

Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>