From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 C9E0921ABB4 for ; Wed, 26 Feb 2025 21:21:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740604895; cv=none; b=lVBZ+pHjIDnHZYT0ml0qR1IivHR1n0Yg3f/Fmb9VL5zob6eQ+HpsR1e91nWfSr1y6rxglrje8fX3AlPgQ4mIYj2KtAgYpBobvdRMiyf5KylZtPkfnHV8e4UN5Gq/QDhwuz+kI5EX858FUthbzI0KvDRmshZN72nwcsZJeWyUx2A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740604895; c=relaxed/simple; bh=lFwz3D/dJstUlIAZUhfh+q8uW7RrJiXD9rCUq9bq77o=; h=Date:To:From:Subject:Message-Id; b=Kdz08TskZus0pI/ohYhVbKBd+4h5SXwH8NsHkWfcbYErDd/EN4bDpl3I+EyAVuudtHt9IhAL8ths+9hP0osANOfZvCGaXRSXSokcEZjRZB+OYQChzYUlXYWSggFoULSGJCnwi0QBuEiW/Mz51G07++gpJ+IQZC3MAUhcx/tvXK8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=UjgW6115; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="UjgW6115" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3B06BC4CEE7; Wed, 26 Feb 2025 21:21:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1740604895; bh=lFwz3D/dJstUlIAZUhfh+q8uW7RrJiXD9rCUq9bq77o=; h=Date:To:From:Subject:From; b=UjgW6115aytPo/Qt3Sx0AKYiouTMlF1z15o2mwR7CHkPNM1WA9OWwKFPGBR5NLy5d Im3LH+8DZbGzitnWNeEUdhd8qt5AkhTACKnM/gYcgydFUB5/OC2aCnuEr/9UVUHuNO lkq/OsaSN/gGTE/sH+rzfW7dMzRT7adwpd0ToMtg= Date: Wed, 26 Feb 2025 13:21:34 -0800 To: mm-commits@vger.kernel.org,yuzhao@google.com,yang@os.amperecomputing.com,willy@infradead.org,wangkefeng.wang@huawei.com,ryan.roberts@arm.com,linmiaohe@huawei.com,kirill.shutemov@linux.intel.com,kasong@tencent.com,jhubbard@nvidia.com,hughd@google.com,david@redhat.com,baolin.wang@linux.alibaba.com,ziy@nvidia.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-shmem-use-xas_try_split-in-shmem_split_large_entry.patch added to mm-unstable branch Message-Id: <20250226212135.3B06BC4CEE7@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/shmem: use xas_try_split() in shmem_split_large_entry() has been added to the -mm mm-unstable branch. Its filename is mm-shmem-use-xas_try_split-in-shmem_split_large_entry.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-shmem-use-xas_try_split-in-shmem_split_large_entry.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Zi Yan Subject: mm/shmem: use xas_try_split() in shmem_split_large_entry() Date: Wed, 26 Feb 2025 16:08:54 -0500 During shmem_split_large_entry(), large swap entries are covering n slots and an order-0 folio needs to be inserted. Instead of splitting all n slots, only the 1 slot covered by the folio need to be split and the remaining n-1 shadow entries can be retained with orders ranging from 0 to n-1. This method only requires (n/XA_CHUNK_SHIFT) new xa_nodes instead of (n % XA_CHUNK_SHIFT) * (n/XA_CHUNK_SHIFT) new xa_nodes, compared to the original xas_split_alloc() + xas_split() one. For example, to split an order-9 large swap entry (assuming XA_CHUNK_SHIFT is 6), 1 xa_node is needed instead of 8. xas_try_split_min_order() is used to reduce the number of calls to xas_try_split() during split. Link: https://lkml.kernel.org/r/20250226210854.2045816-3-ziy@nvidia.com Signed-off-by: Zi Yan Cc: Baolin Wang Cc: Hugh Dickins Cc: Kairui Song Cc: Mattew Wilcox Cc: Miaohe Lin Cc: David Hildenbrand Cc: John Hubbard Cc: Kefeng Wang Cc: Kirill A. Shuemov Cc: Ryan Roberts Cc: Yang Shi Cc: Yu Zhao Signed-off-by: Andrew Morton --- mm/shmem.c | 59 ++++++++++++++++++++++++--------------------------- 1 file changed, 28 insertions(+), 31 deletions(-) --- a/mm/shmem.c~mm-shmem-use-xas_try_split-in-shmem_split_large_entry +++ a/mm/shmem.c @@ -2162,15 +2162,16 @@ static int shmem_split_large_entry(struc { struct address_space *mapping = inode->i_mapping; XA_STATE_ORDER(xas, &mapping->i_pages, index, 0); - void *alloced_shadow = NULL; - int alloced_order = 0, i; + int split_order = 0, entry_order; + int i; /* Convert user data gfp flags to xarray node gfp flags */ gfp &= GFP_RECLAIM_MASK; for (;;) { - int order = -1, split_order = 0; void *old = NULL; + int cur_order; + pgoff_t swap_index; xas_lock_irq(&xas); old = xas_load(&xas); @@ -2179,60 +2180,56 @@ static int shmem_split_large_entry(struc goto unlock; } - order = xas_get_order(&xas); + entry_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; - } + if (!entry_order) + goto unlock; /* Try to split large swap entry in pagecache */ - if (order > 0) { - if (!alloced_order) { - split_order = order; + cur_order = entry_order; + swap_index = round_down(index, 1 << entry_order); + + split_order = xas_try_split_min_order(cur_order); + + while (cur_order > 0) { + pgoff_t aligned_index = + round_down(index, 1 << cur_order); + pgoff_t swap_offset = aligned_index - swap_index; + + xas_set_order(&xas, index, split_order); + xas_try_split(&xas, old, cur_order); + if (xas_error(&xas)) 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++) { - pgoff_t aligned_index = round_down(index, 1 << order); + for (i = 0; i < 1 << cur_order; + i += (1 << split_order)) { swp_entry_t tmp; - tmp = swp_entry(swp_type(swap), swp_offset(swap) + i); + tmp = swp_entry(swp_type(swap), + swp_offset(swap) + swap_offset + + i); __xa_store(&mapping->i_pages, aligned_index + i, swp_to_radix_entry(tmp), 0); } + cur_order = split_order; + split_order = xas_try_split_min_order(split_order); } 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; + return entry_order; } /* _ Patches currently in -mm which might be from ziy@nvidia.com are selftests-mm-make-file-backed-thp-split-work-by-writing-pmd-size-data.patch mm-huge_memory-allow-split-shmem-large-folio-to-any-lower-order.patch selftests-mm-test-splitting-file-backed-thp-to-any-lower-order.patch xarray-add-xas_try_split-to-split-a-multi-index-entry.patch mm-huge_memory-add-two-new-not-yet-used-functions-for-folio_split.patch mm-huge_memory-move-folio-split-common-code-to-__folio_split.patch mm-huge_memory-add-buddy-allocator-like-non-uniform-folio_split.patch mm-huge_memory-remove-the-old-unused-__split_huge_page.patch mm-huge_memory-add-folio_split-to-debugfs-testing-interface.patch mm-truncate-use-buddy-allocator-like-folio-split-for-truncate-operation.patch selftests-mm-add-tests-for-folio_split-buddy-allocator-like-split.patch mm-filemap-use-xas_try_split-in-__filemap_add_folio.patch mm-shmem-use-xas_try_split-in-shmem_split_large_entry.patch