From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-199.mta0.migadu.com [91.218.175.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 04EA23CE0A0 for ; Sun, 4 Oct 2026 03:08:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791083340; cv=none; b=GahAE/yLFIFlz2Llix4uZ3QnUS35/sF9dJdvHwe13Cj1+P87/cdvc8wKjNLRBm05YZ3zfXa6KWwndc/lEGekG4EeOiKgzOx1zHnRGi+Av4qfdKXSjMXPTy3o3VfM5sPgd/TSidMmZG3jngiBG1rRXMFFTH/Tw/F1QafiMv1xXE4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791083340; c=relaxed/simple; bh=Zp+qhYqMQRqCv6BwNrcY760zp89XnNnv158s2z7q+38=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=FIu0Wi55AkfQQq6zmxJXL9l7P8JW8s3eO1XifqHJ/dq/qlK/fHKjuBTp/PETScsl9vqDZfqVmq9Q3MQV4kGhsTmHuDQMCbZVSGPSHIh7KISUVPHQ1edAd9h9aurBmsh/9X2pvsrMeGlsMPRQ+GvRdp8acGwRdNtxF8Un9VJAFKo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=tE8PCqW3; arc=none smtp.client-ip=91.218.175.199 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) header.d=linux.dev header.i=@linux.dev header.b="tE8PCqW3" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=Zp+qhYqMQRqCv6BwNrcY760zp89XnNnv158s2z7q+38=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1791083336; v=1; x=1791688136; b=tE8PCqW39VFf9eNWbocwa/um4Qf9yGxhM6PKF4E+5H50qOTkOHvDGBO9BC1Z2tSHmCpIBaAV b8vUmp/pUcZ2nvj4a+giBDlnFopW6tClAxLbWO+GZk3jtv/xGHdWFaveU25kcK2GI+ancW3v/be vFeIGkE6zAX9A+fELraecCyw= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 5eb3b10a722064f6; Sun, 04 Oct 2026 03:08:55 +0000 X-Mizu-Trace-ID: 5eb3b10a722064f6 X-Migadu-Flow: FLOW_OUT From: Lance Yang To: usama.arif@linux.dev Cc: akpm@linux-foundation.org, david@kernel.org, chrisl@kernel.org, kasong@tencent.com, ljs@kernel.org, ziy@nvidia.com, linux-mm@kvack.org, ying.huang@linux.alibaba.com, baoquan.he@linux.dev, willy@infradead.org, youngjun.park@lge.com, hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev, alex@ghiti.fr, kas@kernel.org, baohua@kernel.org, dev.jain@arm.com, baolin.wang@linux.alibaba.com, nico.pache@linux.dev, liam@infradead.org, ryan.roberts@arm.com, vbabka@kernel.org, lance.yang@linux.dev, linux-kernel@vger.kernel.org, nphamcs@gmail.com, shikemeng@huaweicloud.com, yosry@kernel.org, qi.zheng@linux.dev, luizcap@redhat.com, kernel-team@meta.com Subject: Re: [PATCH v8 00/30] mm: PMD-level swap entries for anonymous THPs Date: Sun, 4 Oct 2026 11:08:44 +0800 Message-ID: <20261004030844.90483-1-lance.yang@linux.dev> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20261002095503.3585565-1-usama.arif@linux.dev> References: <20261002095503.3585565-1-usama.arif@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Hey Usama, Staring at the swap-entry bits across architectures, and RISC-V looks a bit off in that regard ... With Svrsw60t59b and CONFIG_MEM_SOFT_DIRTY=y, setting swap soft-dirty also sets _PAGE_EXEC. A migration PMD then looks present ... so the fault handler skips the migration wait :( And yeah, this is a pre-existing bug. I've sent a separate fix for it. https://lore.kernel.org/linux-mm/20261004030312.90163-1-lance.yang@linux.dev/ BTW, could we also add more checks to pmd_leaf_soft_dirty_tests() so we catch this kind of issue early? Setting a swap flag shouldn't make a non-present PMD present, IIUC. ---8<--- diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c index 863111c6d4eb..80686e2baaa1 100644 --- a/mm/debug_vm_pgtable.c +++ b/mm/debug_vm_pgtable.c @@ -762,7 +762,9 @@ static void __init pmd_leaf_soft_dirty_tests(struct pgtable_debug_args *args) WARN_ON(!pmd_is_huge(pmd)); WARN_ON(!pmd_is_valid_softleaf(pmd)); - WARN_ON(!pmd_swp_soft_dirty(pmd_swp_mksoft_dirty(pmd))); + pmd = pmd_swp_mksoft_dirty(pmd); + WARN_ON(!pmd_swp_soft_dirty(pmd)); + WARN_ON(pmd_present(pmd)); WARN_ON(pmd_swp_soft_dirty(pmd_swp_clear_soft_dirty(pmd))); } #else /* !CONFIG_TRANSPARENT_HUGEPAGE */ -- [...] Cheers, Lance