From nobody Wed Feb 11 10:01:58 2026 Received: from out30-111.freemail.mail.aliyun.com (out30-111.freemail.mail.aliyun.com [115.124.30.111]) (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 D863479B9D for ; Tue, 21 May 2024 11:03:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.111 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716289433; cv=none; b=cr0H+VLJdIsQYMhWcN9KjG9hfR+vfP87/4KVqA0bI/uVebuxPJY9s1FbGfOfhysWFdGRH2vg9A9NbcKvVQp5jN3aQYj4hi6VDQGI6mq/FH8pkBReNXq3GClob5CxRAs9NE/tLDqlLheHv3QmTpEV6BHAiRuZeFjBcZy+XPNTyVQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716289433; c=relaxed/simple; bh=gsjyHEcCKLsatizaYh93zXZYrs2WIQaycqvPWmajK+I=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=RK+nNBY5oF+BmZbTF1xlwHDxntdILSNLL7Fvae0ZUfn6U7xubykbn9BhDBF1yYSHeyUZ6CsuVwfQ1T4+fU/AQpc1VAR5cF48ELaOO2XJOJ8REjgoyXTzSXLqxst5m2QWiohQWQZBWFCvaLUlM0b8YsjhsVcsuJGoorqqrt4jyFY= 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=JSbbCpxS; arc=none smtp.client-ip=115.124.30.111 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="JSbbCpxS" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1716289424; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=3ZBjHevxDMMp9OTvEWxh5sKqkBiotmw21gIhPQdkVy8=; b=JSbbCpxSuHCmM8c8wQVf7vJ92cG/QxZ9CgqZn8gfNjkl1dkF+01Sx0t1M9gEimdaz/cssXeJpAmw+ZMx9yede5bRvO9tEThPVavcjSG6um/Kt7J7zxhOoFk/YhXXH2wXEuFfm0wf/lMDZgu6zO65tXQohpf0OVhk/2reNUSXYHo= X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R551e4;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_---0W6xl98k_1716289421; Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0W6xl98k_1716289421) by smtp.aliyun-inc.com; Tue, 21 May 2024 19:03:42 +0800 From: Baolin Wang To: akpm@linux-foundation.org, hughd@google.com Cc: willy@infradead.org, david@redhat.com, ioworker0@gmail.com, hrisl@kernel.org, p.raghav@samsung.com, da.gomez@samsung.com, wangkefeng.wang@huawei.com, ying.huang@intel.com, 21cnbao@gmail.com, ryan.roberts@arm.com, shy828301@gmail.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH 8/8] mm: shmem: support large folio swap out Date: Tue, 21 May 2024 19:03:18 +0800 Message-Id: <1f50ac5f9dfa69c3c7cc57440eae2b1728178cca.1716285099.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: quoted-printable Content-Type: text/plain; charset="utf-8" Shmem will support large folio allocation [1] [2] to get a better performan= ce, however, the memory reclaim still splits the precious large folios when try= ing to swap out shmem, which may lead to the memory fragmentation issue and can= not take advantage of the large folio for shmeme. Moreover, the swap code already supports for swapping out large folio witho= ut split, hence this patch set supports the large folio swap out for shmem. Note the i915_gem_shmem driver still need to be split when swapping, thus add a new flag 'split_large_folio' for writeback_control to indicate spliti= ng the large folio. [1] https://lore.kernel.org/all/cover.1715571279.git.baolin.wang@linux.alib= aba.com/ [2] https://lore.kernel.org/all/20240515055719.32577-1-da.gomez@samsung.com/ Signed-off-by: Baolin Wang --- drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 1 + include/linux/writeback.h | 1 + mm/shmem.c | 3 +-- mm/vmscan.c | 14 ++++++++++++-- 4 files changed, 15 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i9= 15/gem/i915_gem_shmem.c index 38b72d86560f..968274be14ef 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c @@ -308,6 +308,7 @@ void __shmem_writeback(size_t size, struct address_spac= e *mapping) .range_start =3D 0, .range_end =3D LLONG_MAX, .for_reclaim =3D 1, + .split_large_folio =3D 1, }; unsigned long i; =20 diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 112d806ddbe4..6f2599244ae0 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -63,6 +63,7 @@ struct writeback_control { unsigned range_cyclic:1; /* range_start is cyclic */ unsigned for_sync:1; /* sync(2) WB_SYNC_ALL writeback */ unsigned unpinned_netfs_wb:1; /* Cleared I_PINNING_NETFS_WB */ + unsigned split_large_folio:1; /* Split large folio for shmem writeback */ =20 /* * When writeback IOs are bounced through async layers, only the diff --git a/mm/shmem.c b/mm/shmem.c index fdc71e14916c..6645169aa913 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -776,7 +776,6 @@ static int shmem_add_to_page_cache(struct folio *folio, VM_BUG_ON_FOLIO(index !=3D round_down(index, nr), folio); VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); VM_BUG_ON_FOLIO(!folio_test_swapbacked(folio), folio); - VM_BUG_ON(expected && folio_test_large(folio)); =20 folio_ref_add(folio, nr); folio->mapping =3D mapping; @@ -1460,7 +1459,7 @@ static int shmem_writepage(struct page *page, struct = writeback_control *wbc) * "force", drivers/gpu/drm/i915/gem/i915_gem_shmem.c gets huge pages, * and its shmem_writeback() needs them to be split when swapping. */ - if (folio_test_large(folio)) { + if (wbc->split_large_folio && folio_test_large(folio)) { /* Ensure the subpages are still dirty */ folio_test_set_dirty(folio); if (split_huge_page(page) < 0) diff --git a/mm/vmscan.c b/mm/vmscan.c index bf11c0cbf12e..856286e84d62 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1260,8 +1260,12 @@ static unsigned int shrink_folio_list(struct list_he= ad *folio_list, if (!total_swap_pages) goto activate_locked; =20 - /* Split shmem folio */ - if (split_folio_to_list(folio, folio_list)) + /* + * Only split shmem folio when CONFIG_THP_SWAP + * is not enabled. + */ + if (!IS_ENABLED(CONFIG_THP_SWAP) && + split_folio_to_list(folio, folio_list)) goto keep_locked; } =20 @@ -1363,10 +1367,16 @@ static unsigned int shrink_folio_list(struct list_h= ead *folio_list, * starts and then write it out here. */ try_to_unmap_flush_dirty(); +try_pageout: switch (pageout(folio, mapping, &plug)) { case PAGE_KEEP: goto keep_locked; case PAGE_ACTIVATE: + if (shmem_mapping(mapping) && folio_test_large(folio) && + !split_folio_to_list(folio, folio_list)) { + nr_pages =3D 1; + goto try_pageout; + } goto activate_locked; case PAGE_SUCCESS: stat->nr_pageout +=3D nr_pages; --=20 2.39.3