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Shutemov" , Yang Shi , David Hildenbrand , Hugh Dickins , linux-kernel@vger.kernel.org, David Stevens Subject: [PATCH v4 1/3] mm/khugepaged: refactor collapse_file control flow Date: Fri, 17 Feb 2023 17:54:37 +0900 Message-Id: <20230217085439.2826375-2-stevensd@google.com> X-Mailer: git-send-email 2.39.2.637.g21b0678d19-goog In-Reply-To: <20230217085439.2826375-1-stevensd@google.com> References: <20230217085439.2826375-1-stevensd@google.com> MIME-Version: 1.0 X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 82FDD40010 X-Stat-Signature: w5e5fyg3m9spmkhp3oq7c17h155j439m X-HE-Tag: 1676624107-440415 X-HE-Meta: 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 8DnwIUQM NOehSnwSO41CMWnmB8GNJO8DB4teSukawqNbta+7Mc5q5KjzZOrSY46s/i0V+Ch8D7ohCkKNQL8falg2Auv+buW2R0JPRWBiJNr/elbUzsZbpxwIwZ2u0Hwev57kCiT6BpxRqA9/YdFqUAodAepIC4eOzWt03dsTmEyk0cyw14YnSZCpKz2B2cLW0UlAyj6BoJ57XkdaZf2LDs4DN8/nZFvbr2OLGVXb5Sw7dFpoRdx6JB0kV4XQ6nrgDsNpuxbP6qQFufwg7RdU6brxq67g7qD1iCZfOzZGdGtFFdQ/fzsBXuGPP46Q5ov3MuklmhLPLSMmNqt9jUXSfZntFOqQCbQw7fpLhECHmRRoZUigaNtFaDBY= 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: From: David Stevens Add a rollback label to deal with failure, instead of continuously checking for RESULT_SUCCESS, to make it easier to add more failure cases. The refactoring also allows the collapse_file tracepoint to include hpage on success (instead of NULL). Signed-off-by: David Stevens Acked-by: Peter Xu --- mm/khugepaged.c | 223 ++++++++++++++++++++++++------------------------ 1 file changed, 110 insertions(+), 113 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 8dbc39896811..6a3d6d2e25e0 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1885,6 +1885,12 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, if (result != SCAN_SUCCEED) goto out; + __SetPageLocked(hpage); + if (is_shmem) + __SetPageSwapBacked(hpage); + hpage->index = start; + hpage->mapping = mapping; + /* * Ensure we have slots for all the pages in the range. This is * almost certainly a no-op because most of the pages must be present @@ -1897,16 +1903,10 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, xas_unlock_irq(&xas); if (!xas_nomem(&xas, GFP_KERNEL)) { result = SCAN_FAIL; - goto out; + goto rollback; } } while (1); - __SetPageLocked(hpage); - if (is_shmem) - __SetPageSwapBacked(hpage); - hpage->index = start; - hpage->mapping = mapping; - /* * At this point the hpage is locked and not up-to-date. * It's safe to insert it into the page cache, because nobody would @@ -2123,131 +2123,128 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, */ try_to_unmap_flush(); - if (result == SCAN_SUCCEED) { - /* - * Replacing old pages with new one has succeeded, now we - * attempt to copy the contents. - */ - index = start; - list_for_each_entry(page, &pagelist, lru) { - while (index < page->index) { - clear_highpage(hpage + (index % HPAGE_PMD_NR)); - index++; - } - if (copy_mc_page(hpage + (page->index % HPAGE_PMD_NR), - page) > 0) { - result = SCAN_COPY_MC; - break; - } - index++; - } - while (result == SCAN_SUCCEED && index < end) { + if (result != SCAN_SUCCEED) + goto rollback; + + /* + * Replacing old pages with new one has succeeded, now we + * attempt to copy the contents. + */ + index = start; + list_for_each_entry(page, &pagelist, lru) { + while (index < page->index) { clear_highpage(hpage + (index % HPAGE_PMD_NR)); index++; } + if (copy_mc_page(hpage + (page->index % HPAGE_PMD_NR), + page) > 0) { + result = SCAN_COPY_MC; + goto rollback; + } + index++; + } + while (index < end) { + clear_highpage(hpage + (index % HPAGE_PMD_NR)); + index++; } - if (result == SCAN_SUCCEED) { - /* - * Copying old pages to huge one has succeeded, now we - * need to free the old pages. - */ - list_for_each_entry_safe(page, tmp, &pagelist, lru) { - list_del(&page->lru); - page->mapping = NULL; - page_ref_unfreeze(page, 1); - ClearPageActive(page); - ClearPageUnevictable(page); - unlock_page(page); - put_page(page); - } + /* + * Copying old pages to huge one has succeeded, now we + * need to free the old pages. + */ + list_for_each_entry_safe(page, tmp, &pagelist, lru) { + list_del(&page->lru); + page->mapping = NULL; + page_ref_unfreeze(page, 1); + ClearPageActive(page); + ClearPageUnevictable(page); + unlock_page(page); + put_page(page); + } - xas_lock_irq(&xas); - if (is_shmem) - __mod_lruvec_page_state(hpage, NR_SHMEM_THPS, nr); - else - __mod_lruvec_page_state(hpage, NR_FILE_THPS, nr); + xas_lock_irq(&xas); + if (is_shmem) + __mod_lruvec_page_state(hpage, NR_SHMEM_THPS, nr); + else + __mod_lruvec_page_state(hpage, NR_FILE_THPS, nr); + + if (nr_none) { + __mod_lruvec_page_state(hpage, NR_FILE_PAGES, nr_none); + /* nr_none is always 0 for non-shmem. */ + __mod_lruvec_page_state(hpage, NR_SHMEM, nr_none); + } + /* Join all the small entries into a single multi-index entry. */ + xas_set_order(&xas, start, HPAGE_PMD_ORDER); + xas_store(&xas, hpage); + xas_unlock_irq(&xas); - if (nr_none) { - __mod_lruvec_page_state(hpage, NR_FILE_PAGES, nr_none); - /* nr_none is always 0 for non-shmem. */ - __mod_lruvec_page_state(hpage, NR_SHMEM, nr_none); - } - /* Join all the small entries into a single multi-index entry. */ - xas_set_order(&xas, start, HPAGE_PMD_ORDER); - xas_store(&xas, hpage); - xas_unlock_irq(&xas); + folio = page_folio(hpage); + folio_mark_uptodate(folio); + folio_ref_add(folio, HPAGE_PMD_NR - 1); - folio = page_folio(hpage); - folio_mark_uptodate(folio); - folio_ref_add(folio, HPAGE_PMD_NR - 1); + if (is_shmem) + folio_mark_dirty(folio); + folio_add_lru(folio); - if (is_shmem) - folio_mark_dirty(folio); - folio_add_lru(folio); + /* + * Remove pte page tables, so we can re-fault the page as huge. + */ + result = retract_page_tables(mapping, start, mm, addr, hpage, + cc); + unlock_page(hpage); + goto out; + +rollback: + /* Something went wrong: roll back page cache changes */ + xas_lock_irq(&xas); + if (nr_none) { + mapping->nrpages -= nr_none; + shmem_uncharge(mapping->host, nr_none); + } - /* - * Remove pte page tables, so we can re-fault the page as huge. - */ - result = retract_page_tables(mapping, start, mm, addr, hpage, - cc); - unlock_page(hpage); - hpage = NULL; - } else { - /* Something went wrong: roll back page cache changes */ - xas_lock_irq(&xas); - if (nr_none) { - mapping->nrpages -= nr_none; - shmem_uncharge(mapping->host, nr_none); + xas_set(&xas, start); + xas_for_each(&xas, page, end - 1) { + page = list_first_entry_or_null(&pagelist, + struct page, lru); + if (!page || xas.xa_index < page->index) { + if (!nr_none) + break; + nr_none--; + /* Put holes back where they were */ + xas_store(&xas, NULL); + continue; } - xas_set(&xas, start); - xas_for_each(&xas, page, end - 1) { - page = list_first_entry_or_null(&pagelist, - struct page, lru); - if (!page || xas.xa_index < page->index) { - if (!nr_none) - break; - nr_none--; - /* Put holes back where they were */ - xas_store(&xas, NULL); - continue; - } + VM_BUG_ON_PAGE(page->index != xas.xa_index, page); - VM_BUG_ON_PAGE(page->index != xas.xa_index, page); + /* Unfreeze the page. */ + list_del(&page->lru); + page_ref_unfreeze(page, 2); + xas_store(&xas, page); + xas_pause(&xas); + xas_unlock_irq(&xas); + unlock_page(page); + putback_lru_page(page); + xas_lock_irq(&xas); + } + VM_BUG_ON(nr_none); + /* + * Undo the updates of filemap_nr_thps_inc for non-SHMEM file only. + * This undo is not needed unless failure is due to SCAN_COPY_MC. + */ + if (!is_shmem && result == SCAN_COPY_MC) + filemap_nr_thps_dec(mapping); - /* Unfreeze the page. */ - list_del(&page->lru); - page_ref_unfreeze(page, 2); - xas_store(&xas, page); - xas_pause(&xas); - xas_unlock_irq(&xas); - unlock_page(page); - putback_lru_page(page); - xas_lock_irq(&xas); - } - VM_BUG_ON(nr_none); - /* - * Undo the updates of filemap_nr_thps_inc for non-SHMEM file only. - * This undo is not needed unless failure is due to SCAN_COPY_MC. - */ - if (!is_shmem && result == SCAN_COPY_MC) - filemap_nr_thps_dec(mapping); + xas_unlock_irq(&xas); - xas_unlock_irq(&xas); + hpage->mapping = NULL; - hpage->mapping = NULL; - } + unlock_page(hpage); + mem_cgroup_uncharge(page_folio(hpage)); + put_page(hpage); - if (hpage) - unlock_page(hpage); out: VM_BUG_ON(!list_empty(&pagelist)); - if (hpage) { - mem_cgroup_uncharge(page_folio(hpage)); - put_page(hpage); - } - trace_mm_khugepaged_collapse_file(mm, hpage, index, is_shmem, addr, file, nr, result); return result; }