From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.126.com (m16.mail.126.com [220.197.31.8]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 5D02E61FE7; Wed, 3 Jul 2024 11:15:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.8 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720005365; cv=none; b=TOKxfCoBrJ/rk1giVIEOHUjCDxTRWDwXvdj4ePnLqgVYwNyL3TUHtQGVhenUyP3IYbdDasObwJs7AA4ktZ0NIOkgZNXrK4p+xkPPS3vGsVGXGty5br4zD20cLbC3AMiWjdz17jig8PP8Dy+14K0xtJ6B8q0wqerqEp+phd0Qk8M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720005365; c=relaxed/simple; bh=juOIZ9AODlDarDJeGQRbnLsc+RdH2QSf6K1bsVyvsMo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=iCjdDQrp82KEgiJWAYKx4j56BLH1IKaa61V1rn2ahQnjoV+pYPjFH1w5GQXza/hw9aQLePG9oQSnTojippKoWD2Mt4iNs4eB6UcwqhZ+HlCgyXqtbOZjBCK332VLSeL4TVLLiQvkIcQW8BybdpX4O4PpvUP+QDjZksR+myJOCCA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=126.com; spf=pass smtp.mailfrom=126.com; dkim=pass (1024-bit key) header.d=126.com header.i=@126.com header.b=lTaJyjns; arc=none smtp.client-ip=220.197.31.8 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=126.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=126.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=126.com header.i=@126.com header.b="lTaJyjns" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=126.com; s=s110527; h=Message-ID:Date:MIME-Version:Subject:From: Content-Type; bh=Q42ysf7Ux/6y3GzYGr+UkZ7htmtWB+6tElFWJ0Z5Pms=; b=lTaJyjnscpY+tCKv9KDv6VVgz1qPRpLaCGQAP2wCQRniqxAczMJQSyL47PBpu8 pt9mpA/C7OF6auqyvKe9qOyPWiWDcCqGmqcL4VvbbPcpSlrGqpVnYkDq7QlhQTS7 bwY/0Wkx6enOxqxAzmMXkwcA9VUFZXXJo0rVU34WOINYY= Received: from [172.21.22.210] (unknown [118.242.3.34]) by gzga-smtp-mta-g0-4 (Coremail) with SMTP id _____wD3P4_UMoVmXL0xAQ--.30814S2; Wed, 03 Jul 2024 19:15:33 +0800 (CST) Message-ID: Date: Wed, 3 Jul 2024 19:15:32 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V2] mm/gup: Clear the LRU flag of a page before adding to LRU batch To: Barry Song <21cnbao@gmail.com> Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, david@redhat.com, baolin.wang@linux.alibaba.com, liuzixing@hygon.cn References: <1719038884-1903-1-git-send-email-yangge1116@126.com> From: Ge Yang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CM-TRANSID:_____wD3P4_UMoVmXL0xAQ--.30814S2 X-Coremail-Antispam: 1Uf129KBjvJXoWxKF4UGrWfGr15Jr48GFW8tFb_yoW7ZFW8pF WxGrnIqFWDGFsrur47Xr15AF1Fk393XF4UAFWxGFy7AFn8Z3WqkF1xKw1Uua9xAr15uFn7 u3WUXFnYg3WUJFJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07jYOJ5UUUUU= X-CM-SenderInfo: 51dqwwjhrrila6rslhhfrp/1tbiWRURG2VLbI6TgQABsZ 在 2024/7/3 17:46, Barry Song 写道: > On Sat, Jun 22, 2024 at 6:48 PM wrote: >> >> From: yangge >> >> If a large number of CMA memory are configured in system (for example, the >> CMA memory accounts for 50% of the system memory), starting a virtual >> virtual machine, it will call pin_user_pages_remote(..., FOLL_LONGTERM, >> ...) to pin memory. Normally if a page is present and in CMA area, >> pin_user_pages_remote() will migrate the page from CMA area to non-CMA >> area because of FOLL_LONGTERM flag. But the current code will cause the >> migration failure due to unexpected page refcounts, and eventually cause >> the virtual machine fail to start. >> >> If a page is added in LRU batch, its refcount increases one, remove the >> page from LRU batch decreases one. Page migration requires the page is not >> referenced by others except page mapping. Before migrating a page, we >> should try to drain the page from LRU batch in case the page is in it, >> however, folio_test_lru() is not sufficient to tell whether the page is >> in LRU batch or not, if the page is in LRU batch, the migration will fail. >> >> To solve the problem above, we modify the logic of adding to LRU batch. >> Before adding a page to LRU batch, we clear the LRU flag of the page so >> that we can check whether the page is in LRU batch by folio_test_lru(page). >> Seems making the LRU flag of the page invisible a long time is no problem, >> because a new page is allocated from buddy and added to the lru batch, >> its LRU flag is also not visible for a long time. >> >> Cc: > > you have Cced stable, what is the fixes tag? Thanks，I will add it in next version. > >> Signed-off-by: yangge >> --- >> mm/swap.c | 43 +++++++++++++++++++++++++++++++------------ >> 1 file changed, 31 insertions(+), 12 deletions(-) >> >> diff --git a/mm/swap.c b/mm/swap.c >> index dc205bd..9caf6b0 100644 >> --- a/mm/swap.c >> +++ b/mm/swap.c >> @@ -211,10 +211,6 @@ static void folio_batch_move_lru(struct folio_batch *fbatch, move_fn_t move_fn) >> for (i = 0; i < folio_batch_count(fbatch); i++) { >> struct folio *folio = fbatch->folios[i]; >> >> - /* block memcg migration while the folio moves between lru */ >> - if (move_fn != lru_add_fn && !folio_test_clear_lru(folio)) >> - continue; >> - >> folio_lruvec_relock_irqsave(folio, &lruvec, &flags); >> move_fn(lruvec, folio); >> >> @@ -255,11 +251,16 @@ static void lru_move_tail_fn(struct lruvec *lruvec, struct folio *folio) >> void folio_rotate_reclaimable(struct folio *folio) >> { >> if (!folio_test_locked(folio) && !folio_test_dirty(folio) && >> - !folio_test_unevictable(folio) && folio_test_lru(folio)) { >> + !folio_test_unevictable(folio)) { >> struct folio_batch *fbatch; >> unsigned long flags; >> >> folio_get(folio); >> + if (!folio_test_clear_lru(folio)) { >> + folio_put(folio); >> + return; >> + } >> + >> local_lock_irqsave(&lru_rotate.lock, flags); >> fbatch = this_cpu_ptr(&lru_rotate.fbatch); >> folio_batch_add_and_move(fbatch, folio, lru_move_tail_fn); >> @@ -352,11 +353,15 @@ static void folio_activate_drain(int cpu) >> >> void folio_activate(struct folio *folio) >> { >> - if (folio_test_lru(folio) && !folio_test_active(folio) && >> - !folio_test_unevictable(folio)) { >> + if (!folio_test_active(folio) && !folio_test_unevictable(folio)) { >> struct folio_batch *fbatch; >> >> folio_get(folio); >> + if (!folio_test_clear_lru(folio)) { >> + folio_put(folio); >> + return; >> + } >> + >> local_lock(&cpu_fbatches.lock); >> fbatch = this_cpu_ptr(&cpu_fbatches.activate); >> folio_batch_add_and_move(fbatch, folio, folio_activate_fn); >> @@ -700,6 +705,11 @@ void deactivate_file_folio(struct folio *folio) >> return; >> >> folio_get(folio); >> + if (!folio_test_clear_lru(folio)) { >> + folio_put(folio); >> + return; >> + } >> + >> local_lock(&cpu_fbatches.lock); >> fbatch = this_cpu_ptr(&cpu_fbatches.lru_deactivate_file); >> folio_batch_add_and_move(fbatch, folio, lru_deactivate_file_fn); >> @@ -716,11 +726,16 @@ void deactivate_file_folio(struct folio *folio) >> */ >> void folio_deactivate(struct folio *folio) >> { >> - if (folio_test_lru(folio) && !folio_test_unevictable(folio) && >> - (folio_test_active(folio) || lru_gen_enabled())) { >> + if (!folio_test_unevictable(folio) && (folio_test_active(folio) || >> + lru_gen_enabled())) { >> struct folio_batch *fbatch; >> >> folio_get(folio); >> + if (!folio_test_clear_lru(folio)) { >> + folio_put(folio); >> + return; >> + } >> + >> local_lock(&cpu_fbatches.lock); >> fbatch = this_cpu_ptr(&cpu_fbatches.lru_deactivate); >> folio_batch_add_and_move(fbatch, folio, lru_deactivate_fn); >> @@ -737,12 +752,16 @@ void folio_deactivate(struct folio *folio) >> */ >> void folio_mark_lazyfree(struct folio *folio) >> { >> - if (folio_test_lru(folio) && folio_test_anon(folio) && >> - folio_test_swapbacked(folio) && !folio_test_swapcache(folio) && >> - !folio_test_unevictable(folio)) { >> + if (folio_test_anon(folio) && folio_test_swapbacked(folio) && >> + !folio_test_swapcache(folio) && !folio_test_unevictable(folio)) { >> struct folio_batch *fbatch; >> >> folio_get(folio); >> + if (!folio_test_clear_lru(folio)) { >> + folio_put(folio); >> + return; >> + } >> + >> local_lock(&cpu_fbatches.lock); >> fbatch = this_cpu_ptr(&cpu_fbatches.lru_lazyfree); >> folio_batch_add_and_move(fbatch, folio, lru_lazyfree_fn); >> -- >> 2.7.4 >>