From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=91.218.175.117 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794454761; b=ZL/mm6HfGUEZwBr2GdEBbGjs//3vqLaSckOAhE6/bwQScsYVY7AfRtccnBUe3uNR/Txf cZJt/t7lloG7bQWLovsbCPflZRnI+5PCKXY85D1fGqQykjy9f7hVgVzH2+YPTxRPc1IVx +/PjFH79F9kW0KxrmHI5WCKzkq3f/UURoPxOgamOf0ttoC3hbRAEeJzNa21LZJmzW1f3t dTyutKnErQtjLMnw39/3HuPJA10++EcUL72AUdBkZc/uxzD+dH6mpptKjpvTHhURYmbI3 y88we8KLUO4mf2Jaunsfm79jCVb3RgPl+z+ZxHMdppT9+gj25vFzG2oFjSsvS7L4YuA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794454761; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:From:Date:Subject:MIME-Version: Content-Type:Content-Transfer-Encoding:Message-Id:X-B4-Tracking:To:Cc: X-Mailer; bh=lN/piXhtdPACOa13WtNqIwYIKwldh3lDc6Fab80206s=; b=NkQKJdHFi0BscTRqTuB2PDeUVpaD9kjEe2ngDXDkr9bdyPS2v9r0MaRMyLXgXe95zxwv JA9Vii6QFamQwStJm0snephLJy0cLS0wj4pLJ8n5F+cH2fINDokiM6QUwFez14yZTDxbY NE3z+v96S+9H4YmI5T8Xir2ZSwVUQUOY5eXC/Pat8vidwZ3cCATYKTVogPS22fT+7DGYg xvyFn6uJpsgeznHMwtJF/fADR8zCG/DUjhLQMLonEoZf5mVPLmwLSsVyPiL3UDotVOU6b 0BK8dr/3Z3ZBzRFtsKohiDLGHyx+rEfDQZigDjbNiRB7ayCvQpcYsmV70rBedjw7GNg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=dFuC2xlQ; arc=none smtp.remote-ip=91.218.175.117 Received: from mta0.migadu.com (out-117.mta0.migadu.com [91.218.175.117]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 44AD3606A31C for ; Thu, 12 Nov 2026 03:39:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 44AD3606A31C Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=dFuC2xlQ X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=WagULwVSRwlFPNiHuU3y1792mcFYfBmerRUsHRfoDYc=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1794454758; v=1; x=1795059558; b=dFuC2xlQS0kBW4rA/SkuuSMMjDzLesUOn3lOhPo3LqBgk+ewSOvk5zl+BH684JbONMg8J5CN 4xRD7QC15enpDveMdaAKmTpkz2+oXbyUIkJa4ZzYbJZ0JQMH6LOyBxA4mXONTZPcf1i5xHKn+rz ciEjwSM/JXXx9dRkBFtehcLw= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id da00386efe8865b5; Thu, 12 Nov 2026 03:39:18 +0000 X-Mizu-Trace-ID: da00386efe8865b5 X-Migadu-Flow: FLOW_OUT From: Qiliang Yuan Date: Wed, 11 Nov 2026 22:39:01 -0500 Subject: [PATCH] mm/shmem: drop the second folio batch from shmem_undo_range() X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261111-bug-mm-shmem-undo-frame-v1-1-e50a95b8f9b2@linux.dev> X-B4-Tracking: v=1; b=H4sIANQ09WoC/x2MywqAIBAAfyX23EIK2eNXooPlantYC6UIon9Pm tscZh7IlJgyjNUDiS7OvMciqq5g3WwMhOyKg260UQVczoAimDchwTO6HX2yQmhMr3tSQ2ddC6U +Enm+//M0v+8HA8ESc2kAAAA= To: Hugh Dickins , Baolin Wang , Andrew Morton , Jan Kara , Qiliang Yuan , "David Hildenbrand (Arm)" Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, kernel test robot , Qiliang Yuan X-Mailer: b4 0.13.0 shmem_undo_range() keeps a folio_batch and an array of FOLIO_BATCH_SIZE indices on its stack. Removing truncated folios from the page cache in batches added a second folio_batch to collect the folios to delete. That grows the stack frame by about 200 bytes, past the 1024 byte limit of mips eyeq6_defconfig built with clang. Pass fbatch itself to delete_from_page_cache_batch() once the swap entries are gone, as truncate_inode_pages_range() does. Undoing a failed fallocate() only removes the folios that are not uptodate, so remove those one at a time with truncate_inode_folio() as before. Stack frame of shmem_undo_range() built with clang 18: config before (bytes) after (bytes) change mips eyeq6_defconfig 928 720 -22% x86_64 920 712 -23% Fixes: b97fbd541ecba ("mm/shmem: remove truncated folios from the page cache in batches") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202611112032.TMyPU6Rm-lkp@intel.com/ Signed-off-by: Qiliang Yuan --- David, this applies on top of b97fbd541ecba in shmem-7.5.misc; please fold it in if you prefer. --- mm/shmem.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index 156469423a866..5bcbdd6078a73 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1352,9 +1352,6 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, uoff_t lend, index = start; while (index < end && find_lock_entries(mapping, &index, end - 1, &fbatch, indices)) { - struct folio_batch remove; - - folio_batch_init(&remove); for (i = 0; i < folio_batch_count(&fbatch); i++) { folio = fbatch.folios[i]; @@ -1366,13 +1363,14 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, uoff_t lend, continue; } - if (!unfalloc || !folio_test_uptodate(folio)) { + if (!unfalloc) truncate_cleanup_folio(folio); - folio_batch_add(&remove, folio); - } + else if (!folio_test_uptodate(folio)) + truncate_inode_folio(mapping, folio); } - delete_from_page_cache_batch(mapping, &remove); folio_batch_remove_exceptionals(&fbatch); + if (!unfalloc) + delete_from_page_cache_batch(mapping, &fbatch); for (i = 0; i < folio_batch_count(&fbatch); i++) folio_unlock(fbatch.folios[i]); folio_batch_release(&fbatch); --- base-commit: b97fbd541ecba5d6640077618e9dfec6f5e71132 change-id: 20261111-bug-mm-shmem-undo-frame-66828e197ad5 Best regards, -- Qiliang Yuan