From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-118.freemail.mail.aliyun.com (out30-118.freemail.mail.aliyun.com [115.124.30.118]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 199A91C9DF9 for ; Wed, 7 Aug 2024 07:31:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.118 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723015902; cv=none; b=t3smyAQ1Sfqr5tGZwlaFpUl3rUzJapm6LgjjhoQ6v7EIVmccHvH+Kiq3WmQF8ziNdlowBFJWqTfwammsBfmwBJjKemjID+ge6Ccx/lEVLeBWqbKbF18IjbWAZ9wg9wlbP/p8042zinrobmyAf3yk+qkU/vI/bLqfEYp36sDQTgg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723015902; c=relaxed/simple; bh=L1tUkGG2sobTCu0i+kAP6ENbalJz5VP6gTOk0FbXJNo=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=gZwxbAtwdVqj9LMoXA7j8CguuBnGzKI8VrrxSXEhkl4UsLXBsF9ItWEMwPz9XMD/hqadu1PfYVOCzQppAnMghGQauHcPRStK5yTXs95GrjeJXv/U4NYI6D37gTQjv9LZsvBZOgX/5vtARZXfIwwCMHILanWlOVtXLZvrUiD+8e0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=UgfIw2Wd; arc=none smtp.client-ip=115.124.30.118 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="UgfIw2Wd" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1723015898; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=PZslh3xDjv8KO1NsIQv9gTqVJj0244TUIWHfHI4JVZY=; b=UgfIw2WdxRh78bu8v7/i60cYDioCVaIgEDugbNAIDKFuJiCbhQ3JbzrqkCF80F1jfxBFHugsGlQWxWskKaawlAEN/1zj//SoGasNHjBYH/YYQP99M6cRHAPn6HhyQhgg8fbYHVnsg4QuUE4IOFw5Ewd7voWGe9jyjt2uslMBB5A= X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R101e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=maildocker-contentspam033037067110;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=17;SR=0;TI=SMTPD_---0WCI9FsZ_1723015896; Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0WCI9FsZ_1723015896) by smtp.aliyun-inc.com; Wed, 07 Aug 2024 15:31:36 +0800 From: Baolin Wang To: akpm@linux-foundation.org, hughd@google.com Cc: willy@infradead.org, david@redhat.com, wangkefeng.wang@huawei.com, chrisl@kernel.org, ying.huang@intel.com, 21cnbao@gmail.com, ryan.roberts@arm.com, shy828301@gmail.com, ziy@nvidia.com, ioworker0@gmail.com, da.gomez@samsung.com, p.raghav@samsung.com, baolin.wang@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 09/10] mm: shmem: split large entry if the swapin folio is not large Date: Wed, 7 Aug 2024 15:31:14 +0800 Message-Id: <7eef2117208a6146ea31e8c87238f1b25519c07c.1723012159.git.baolin.wang@linux.alibaba.com> X-Mailer: git-send-email 2.39.3 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Now the swap device can only swap-in order 0 folio, even though a large folio is swapped out. This requires us to split the large entry previously saved in the shmem pagecache to support the swap in of small folios. Signed-off-by: Baolin Wang --- mm/shmem.c | 100 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 100 insertions(+) diff --git a/mm/shmem.c b/mm/shmem.c index 345e25425e37..996062dc196b 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1990,6 +1990,81 @@ static void shmem_set_folio_swapin_error(struct inode *inode, pgoff_t index, swap_free_nr(swap, nr_pages); } +static int shmem_split_large_entry(struct inode *inode, pgoff_t index, + swp_entry_t swap, int new_order, gfp_t gfp) +{ + struct address_space *mapping = inode->i_mapping; + XA_STATE_ORDER(xas, &mapping->i_pages, index, new_order); + void *alloced_shadow = NULL; + int alloced_order = 0, i; + + for (;;) { + int order = -1, split_order = 0; + void *old = NULL; + + xas_lock_irq(&xas); + old = xas_load(&xas); + if (!xa_is_value(old) || swp_to_radix_entry(swap) != old) { + xas_set_err(&xas, -EEXIST); + goto unlock; + } + + order = xas_get_order(&xas); + + /* Swap entry may have changed before we re-acquire the lock */ + if (alloced_order && + (old != alloced_shadow || order != alloced_order)) { + xas_destroy(&xas); + alloced_order = 0; + } + + /* Try to split large swap entry in pagecache */ + if (order > 0 && order > new_order) { + if (!alloced_order) { + split_order = order; + goto unlock; + } + xas_split(&xas, old, order); + + /* + * Re-set the swap entry after splitting, and the swap + * offset of the original large entry must be continuous. + */ + for (i = 0; i < 1 << order; i += (1 << new_order)) { + pgoff_t aligned_index = round_down(index, 1 << order); + swp_entry_t tmp; + + tmp = swp_entry(swp_type(swap), swp_offset(swap) + i); + __xa_store(&mapping->i_pages, aligned_index + i, + swp_to_radix_entry(tmp), 0); + } + } + +unlock: + xas_unlock_irq(&xas); + + /* split needed, alloc here and retry. */ + if (split_order) { + xas_split_alloc(&xas, old, split_order, gfp); + if (xas_error(&xas)) + goto error; + alloced_shadow = old; + alloced_order = split_order; + xas_reset(&xas); + continue; + } + + if (!xas_nomem(&xas, gfp)) + break; + } + +error: + if (xas_error(&xas)) + return xas_error(&xas); + + return alloced_order; +} + /* * Swap in the folio pointed to by *foliop. * Caller has to make sure that *foliop contains a valid swapped folio. @@ -2026,12 +2101,37 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index, /* Look it up and read it in.. */ folio = swap_cache_get_folio(swap, NULL, 0); if (!folio) { + int split_order; + /* Or update major stats only when swapin succeeds?? */ if (fault_type) { *fault_type |= VM_FAULT_MAJOR; count_vm_event(PGMAJFAULT); count_memcg_event_mm(fault_mm, PGMAJFAULT); } + + /* + * Now swap device can only swap in order 0 folio, then we + * should split the large swap entry stored in the pagecache + * if necessary. + */ + split_order = shmem_split_large_entry(inode, index, swap, 0, gfp); + if (split_order < 0) { + error = split_order; + goto failed; + } + + /* + * If the large swap entry has already been split, it is + * necessary to recalculate the new swap entry based on + * the old order alignment. + */ + if (split_order > 0) { + pgoff_t offset = index - round_down(index, 1 << split_order); + + swap = swp_entry(swp_type(swap), swp_offset(swap) + offset); + } + /* Here we actually start the io */ folio = shmem_swapin_cluster(swap, gfp, info, index); if (!folio) { -- 2.39.3