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Date: Thu, 3 Dec 2020 00:22:28 -0800
From: John Hubbard <jhubbard@...dia.com>
To: Pavel Tatashin <pasha.tatashin@...een.com>,
<linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
<akpm@...ux-foundation.org>, <vbabka@...e.cz>, <mhocko@...e.com>,
<david@...hat.com>, <osalvador@...e.de>,
<dan.j.williams@...el.com>, <sashal@...nel.org>,
<tyhicks@...ux.microsoft.com>, <iamjoonsoo.kim@....com>,
<mike.kravetz@...cle.com>, <rostedt@...dmis.org>,
<mingo@...hat.com>, <jgg@...pe.ca>, <peterz@...radead.org>,
<mgorman@...e.de>, <willy@...radead.org>, <rientjes@...gle.com>
Subject: Re: [PATCH 6/6] mm/gup: migrate pinned pages out of movable zone
On 12/1/20 9:23 PM, Pavel Tatashin wrote:
> We do not allocate pin pages in ZONE_MOVABLE, but if pages were already
> allocated before pinning they need to migrated to a different zone.
> Currently, we migrate movable CMA pages only. Generalize the function
> that migrates CMA pages to migrate all movable pages.
>
> Signed-off-by: Pavel Tatashin <pasha.tatashin@...een.com>
> ---
> include/linux/migrate.h | 1 +
> include/trace/events/migrate.h | 3 +-
> mm/gup.c | 56 +++++++++++++---------------------
> 3 files changed, 24 insertions(+), 36 deletions(-)
>
I like the cleanup so far, even at this point it's a relief to finally
see the nested ifdefs get removed.
One naming nit/idea below, but this looks fine as is, so:
Reviewed-by: John Hubbard <jhubbard@...dia.com>
> diff --git a/include/linux/migrate.h b/include/linux/migrate.h
> index 0f8d1583fa8e..00bab23d1ee5 100644
> --- a/include/linux/migrate.h
> +++ b/include/linux/migrate.h
> @@ -27,6 +27,7 @@ enum migrate_reason {
> MR_MEMPOLICY_MBIND,
> MR_NUMA_MISPLACED,
> MR_CONTIG_RANGE,
> + MR_LONGTERM_PIN,
> MR_TYPES
> };
>
> diff --git a/include/trace/events/migrate.h b/include/trace/events/migrate.h
> index 4d434398d64d..363b54ce104c 100644
> --- a/include/trace/events/migrate.h
> +++ b/include/trace/events/migrate.h
> @@ -20,7 +20,8 @@
> EM( MR_SYSCALL, "syscall_or_cpuset") \
> EM( MR_MEMPOLICY_MBIND, "mempolicy_mbind") \
> EM( MR_NUMA_MISPLACED, "numa_misplaced") \
> - EMe(MR_CONTIG_RANGE, "contig_range")
> + EM( MR_CONTIG_RANGE, "contig_range") \
> + EMe(MR_LONGTERM_PIN, "longterm_pin")
>
> /*
> * First define the enums in the above macros to be exported to userspace
> diff --git a/mm/gup.c b/mm/gup.c
> index 724d8a65e1df..1d511f65f8a7 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -1593,19 +1593,18 @@ static bool check_dax_vmas(struct vm_area_struct **vmas, long nr_pages)
> }
> #endif
>
> -#ifdef CONFIG_CMA
> -static long check_and_migrate_cma_pages(struct mm_struct *mm,
> - unsigned long start,
> - unsigned long nr_pages,
> - struct page **pages,
> - struct vm_area_struct **vmas,
> - unsigned int gup_flags)
> +static long check_and_migrate_movable_pages(struct mm_struct *mm,
> + unsigned long start,
> + unsigned long nr_pages,
> + struct page **pages,
> + struct vm_area_struct **vmas,
> + unsigned int gup_flags)
> {
> unsigned long i;
> unsigned long step;
> bool drain_allow = true;
> bool migrate_allow = true;
> - LIST_HEAD(cma_page_list);
> + LIST_HEAD(page_list);
Maybe naming it "movable_page_list", would be a nice touch.
thanks,
--
John Hubbard
NVIDIA
> long ret = nr_pages;
> struct migration_target_control mtc = {
> .nid = NUMA_NO_NODE,
> @@ -1623,13 +1622,12 @@ static long check_and_migrate_cma_pages(struct mm_struct *mm,
> */
> step = compound_nr(head) - (pages[i] - head);
> /*
> - * If we get a page from the CMA zone, since we are going to
> - * be pinning these entries, we might as well move them out
> - * of the CMA zone if possible.
> + * If we get a movable page, since we are going to be pinning
> + * these entries, try to move them out if possible.
> */
> - if (is_migrate_cma_page(head)) {
> + if (is_migrate_movable(get_pageblock_migratetype(head))) {
> if (PageHuge(head))
> - isolate_huge_page(head, &cma_page_list);
> + isolate_huge_page(head, &page_list);
> else {
> if (!PageLRU(head) && drain_allow) {
> lru_add_drain_all();
> @@ -1637,7 +1635,7 @@ static long check_and_migrate_cma_pages(struct mm_struct *mm,
> }
>
> if (!isolate_lru_page(head)) {
> - list_add_tail(&head->lru, &cma_page_list);
> + list_add_tail(&head->lru, &page_list);
> mod_node_page_state(page_pgdat(head),
> NR_ISOLATED_ANON +
> page_is_file_lru(head),
> @@ -1649,7 +1647,7 @@ static long check_and_migrate_cma_pages(struct mm_struct *mm,
> i += step;
> }
>
> - if (!list_empty(&cma_page_list)) {
> + if (!list_empty(&page_list)) {
> /*
> * drop the above get_user_pages reference.
> */
> @@ -1659,7 +1657,7 @@ static long check_and_migrate_cma_pages(struct mm_struct *mm,
> for (i = 0; i < nr_pages; i++)
> put_page(pages[i]);
>
> - if (migrate_pages(&cma_page_list, alloc_migration_target, NULL,
> + if (migrate_pages(&page_list, alloc_migration_target, NULL,
> (unsigned long)&mtc, MIGRATE_SYNC, MR_CONTIG_RANGE)) {
> /*
> * some of the pages failed migration. Do get_user_pages
> @@ -1667,17 +1665,16 @@ static long check_and_migrate_cma_pages(struct mm_struct *mm,
> */
> migrate_allow = false;
>
> - if (!list_empty(&cma_page_list))
> - putback_movable_pages(&cma_page_list);
> + if (!list_empty(&page_list))
> + putback_movable_pages(&page_list);
> }
> /*
> * We did migrate all the pages, Try to get the page references
> - * again migrating any new CMA pages which we failed to isolate
> - * earlier.
> + * again migrating any pages which we failed to isolate earlier.
> */
> ret = __get_user_pages_locked(mm, start, nr_pages,
> - pages, vmas, NULL,
> - gup_flags);
> + pages, vmas, NULL,
> + gup_flags);
>
> if ((ret > 0) && migrate_allow) {
> nr_pages = ret;
> @@ -1688,17 +1685,6 @@ static long check_and_migrate_cma_pages(struct mm_struct *mm,
>
> return ret;
> }
> -#else
> -static long check_and_migrate_cma_pages(struct mm_struct *mm,
> - unsigned long start,
> - unsigned long nr_pages,
> - struct page **pages,
> - struct vm_area_struct **vmas,
> - unsigned int gup_flags)
> -{
> - return nr_pages;
> -}
> -#endif /* CONFIG_CMA */
>
> /*
> * __gup_longterm_locked() is a wrapper for __get_user_pages_locked which
> @@ -1746,8 +1732,8 @@ static long __gup_longterm_locked(struct mm_struct *mm,
> goto out;
> }
>
> - rc = check_and_migrate_cma_pages(mm, start, rc, pages,
> - vmas_tmp, gup_flags);
> + rc = check_and_migrate_movable_pages(mm, start, rc, pages,
> + vmas_tmp, gup_flags);
> out:
> memalloc_nomovable_restore(flags);
> }
>
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