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[73.69.118.222]) by smtp.gmail.com with ESMTPSA id z20sm11934536qkz.37.2021.01.18.20.39.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 18 Jan 2021 20:39:41 -0800 (PST) From: Pavel Tatashin To: pasha.tatashin@soleen.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, vbabka@suse.cz, mhocko@suse.com, david@redhat.com, osalvador@suse.de, dan.j.williams@intel.com, sashal@kernel.org, tyhicks@linux.microsoft.com, iamjoonsoo.kim@lge.com, mike.kravetz@oracle.com, rostedt@goodmis.org, mingo@redhat.com, jgg@ziepe.ca, peterz@infradead.org, mgorman@suse.de, willy@infradead.org, rientjes@google.com, jhubbard@nvidia.com, linux-doc@vger.kernel.org, ira.weiny@intel.com, linux-kselftest@vger.kernel.org Subject: [PATCH v5 12/14] mm/gup: longterm pin migration cleaup Date: Mon, 18 Jan 2021 23:39:18 -0500 Message-Id: <20210119043920.155044-13-pasha.tatashin@soleen.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210119043920.155044-1-pasha.tatashin@soleen.com> References: <20210119043920.155044-1-pasha.tatashin@soleen.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: When pages are longterm pinned, we must migrated them out of movable zone= . The function that migrates them has a hidden loop with goto. The loop is to retry on isolation failures, and after successful migration. Make this code better by moving this loop to the caller. Signed-off-by: Pavel Tatashin --- mm/gup.c | 101 +++++++++++++++++++++++-------------------------------- 1 file changed, 42 insertions(+), 59 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index dfe90b254bc6..3b46eb5fe3ba 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1548,27 +1548,28 @@ struct page *get_dump_page(unsigned long addr) } #endif /* CONFIG_ELF_CORE */ =20 -static long check_and_migrate_movable_pages(struct mm_struct *mm, - unsigned long start, - unsigned long nr_pages, +/* + * Check whether all pages are pinnable, if so return number of pages. = If some + * pages are not pinnable, migrate them, and unpin all pages. Return zer= o if + * pages were migrated, or if some pages were not successfully isolated. + * Return negative error if migration fails. + */ +static long check_and_migrate_movable_pages(unsigned long nr_pages, struct page **pages, - struct vm_area_struct **vmas, unsigned int gup_flags) { - unsigned long i, isolation_error_count; - bool drain_allow; + unsigned long i; + unsigned long isolation_error_count =3D 0; + bool drain_allow =3D true; LIST_HEAD(movable_page_list); - long ret =3D nr_pages; - struct page *prev_head, *head; + long ret =3D 0; + struct page *prev_head =3D NULL; + struct page *head; struct migration_target_control mtc =3D { .nid =3D NUMA_NO_NODE, .gfp_mask =3D GFP_USER | __GFP_NOWARN, }; =20 -check_again: - prev_head =3D NULL; - isolation_error_count =3D 0; - drain_allow =3D true; for (i =3D 0; i < nr_pages; i++) { head =3D compound_head(pages[i]); if (head =3D=3D prev_head) @@ -1606,40 +1607,23 @@ static long check_and_migrate_movable_pages(struc= t mm_struct *mm, * in the correct zone. */ if (list_empty(&movable_page_list) && !isolation_error_count) - return ret; + return nr_pages; =20 + if (gup_flags & FOLL_PIN) { + unpin_user_pages(pages, nr_pages); + } else { + for (i =3D 0; i < nr_pages; i++) + put_page(pages[i]); + } if (!list_empty(&movable_page_list)) { - /* - * drop the above get_user_pages reference. - */ - if (gup_flags & FOLL_PIN) - unpin_user_pages(pages, nr_pages); - else - for (i =3D 0; i < nr_pages; i++) - put_page(pages[i]); - ret =3D migrate_pages(&movable_page_list, alloc_migration_target, NULL, (unsigned long)&mtc, MIGRATE_SYNC, MR_LONGTERM_PIN); - if (ret) { - if (!list_empty(&movable_page_list)) - putback_movable_pages(&movable_page_list); - return ret > 0 ? -ENOMEM : ret; - } - - /* We unpinned pages before migration, pin them again */ - ret =3D __get_user_pages_locked(mm, start, nr_pages, pages, vmas, - NULL, gup_flags); - if (ret <=3D 0) - return ret; - nr_pages =3D ret; + if (ret && !list_empty(&movable_page_list)) + putback_movable_pages(&movable_page_list); } =20 - /* - * check again because pages were unpinned, and we also might have - * had isolation errors and need more pages to migrate. - */ - goto check_again; + return ret > 0 ? -ENOMEM : ret; } =20 /* @@ -1653,30 +1637,29 @@ static long __gup_longterm_locked(struct mm_struc= t *mm, struct vm_area_struct **vmas, unsigned int gup_flags) { - unsigned long flags =3D 0; + unsigned int flags; long rc; =20 - if (gup_flags & FOLL_LONGTERM) { - /* - * We are long term pinning pages and their PA's should not - * change until unpinned. Without FOLL_WRITE we might get zero - * page which we do not want. Force creating normal - * pages by adding FOLL_WRITE. - */ - gup_flags |=3D FOLL_WRITE; - flags =3D memalloc_pin_save(); - } + if (!(gup_flags & FOLL_LONGTERM)) + return __get_user_pages_locked(mm, start, nr_pages, pages, vmas, + NULL, gup_flags); + /* + * We are long term pinning pages and their PA's should not change unti= l + * unpinned. Without FOLL_WRITE we might get zero page which we do not + * want. Force creating normal pages by adding FOLL_WRITE. + */ + gup_flags |=3D FOLL_WRITE; + flags =3D memalloc_pin_save(); =20 - rc =3D __get_user_pages_locked(mm, start, nr_pages, pages, vmas, NULL, - gup_flags); + do { + rc =3D __get_user_pages_locked(mm, start, nr_pages, pages, vmas, + NULL, gup_flags); + if (rc <=3D 0) + break; + rc =3D check_and_migrate_movable_pages(rc, pages, gup_flags); + } while (!rc); + memalloc_pin_restore(flags); =20 - if (gup_flags & FOLL_LONGTERM) { - if (rc > 0) - rc =3D check_and_migrate_movable_pages(mm, start, rc, - pages, vmas, - gup_flags); - memalloc_pin_restore(flags); - } return rc; } =20 --=20 2.25.1