The patch titled mm: add comment why mark_page_accessed() would be better than pte_mkyoung() in follow_page() has been removed from the -mm tree. Its filename was mm-add-comment-why-mark_page_accessed-would-be-better-than-pte_mkyoung-in-follow_page.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: mm: add comment why mark_page_accessed() would be better than pte_mkyoung() in follow_page() From: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> At first look, mark_page_accessed() in follow_page() seems a bit strange. It seems pte_mkyoung() would be better consistent with other kernel code. However, it is intentional. The commit log said: ------------------------------------------------ commit 9e45f61d69be9024a2e6bef3831fb04d90fac7a8 Author: akpm <akpm> Date: Fri Aug 15 07:24:59 2003 +0000 [PATCH] Use mark_page_accessed() in follow_page() Touching a page via follow_page() counts as a reference so we should be either setting the referenced bit in the pte or running mark_page_accessed(). Altering the pte is tricky because we haven't implemented an atomic pte_mkyoung(). And mark_page_accessed() is better anyway because it has more aging state: it can move the page onto the active list. BKrev: 3f3c8acbplT8FbwBVGtth7QmnqWkIw ------------------------------------------------ The atomic issue is still true nowadays. adding comment help to understand code intention and it would be better. [akpm@xxxxxxxxxxxxxxxxxxxx: clarify text] Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> Signed-off-by: Hugh Dickins <hugh@xxxxxxxxxxx> Cc: Nick Piggin <npiggin@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/memory.c | 5 +++++ 1 file changed, 5 insertions(+) diff -puN mm/memory.c~mm-add-comment-why-mark_page_accessed-would-be-better-than-pte_mkyoung-in-follow_page mm/memory.c --- a/mm/memory.c~mm-add-comment-why-mark_page_accessed-would-be-better-than-pte_mkyoung-in-follow_page +++ a/mm/memory.c @@ -1151,6 +1151,11 @@ struct page *follow_page(struct vm_area_ if ((flags & FOLL_WRITE) && !pte_dirty(pte) && !PageDirty(page)) set_page_dirty(page); + /* + * pte_mkyoung() would be more correct here, but atomic care + * is needed to avoid losing the dirty bit: it is easier to use + * mark_page_accessed(). + */ mark_page_accessed(page); } unlock: _ Patches currently in -mm which might be from kosaki.motohiro@xxxxxxxxxxxxxx are origin.patch linux-next.patch mm-update_page_reclaim_stat-is-called-from-page-fault-path.patch getrusage-fill-ru_maxrss-value.patch softirq-introduce-statistics-for-softirq.patch proc-export-statistics-for-softirq-to-proc.patch proc-export-statistics-for-softirq-to-proc-fix.patch proc-update-document-for-proc-softirqs-and-proc-stat.patch memcg-remove-mem_cgroup_calc_mapped_ratio-take2.patch memcg-remove-mem_cgroup_reclaim_imbalance-remnants.patch ia64-implement-interrupt-enabling-rwlocks.patch fs-symlink-write_begin-allocation-context-fix-reiser4-fix.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html