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 4D31B30F559 for ; Mon, 18 Aug 2025 11:08:11 +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=1755515291; cv=none; b=Ver5T5xabQbYNFi7yfX59sSN9EC6IhcxXXYurmnxnBNYbMSzP8ivGQcbOAanc2H5dvTbREqRrP0uOJnzySqkgKaOZT0TesiDzVymhgiUVNH7iXxE6eL6FSLRM1Cd1xTRui7+vLWlVsFVGgnlkMTmx1n1BJ+mmUJYYBDRFO6iaq4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755515291; c=relaxed/simple; bh=DdcCIQwrVgh0tNxpryj7sFMNynO8Gh2Q33uCFyPcBKU=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=modtOYvYkfB8H8t4TByq2y9gzysZM9UujV4y7rk/mNEH76m7HjTDnzRsH1oxjOpmbn6gS6JgX70fNs3HMbQ7LbHx5hrell+Au19tdAYG2EvneZ34ZHJI1tAGotHGd3Hwa/ITJRIEYjFqL+jc8C9QKHTifBIQ2GghZiUXhrbV3jE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=SAzave88; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="SAzave88" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7A09BC4CEF1; Mon, 18 Aug 2025 11:08:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1755515291; bh=DdcCIQwrVgh0tNxpryj7sFMNynO8Gh2Q33uCFyPcBKU=; h=Subject:To:Cc:From:Date:From; b=SAzave88t00sPckpWoJMWPY7p3NhzL3uc4u1rdWE5aE10JCRWskTJKlctvFD5MIhU eRgG5kfm3FmF3jp1rd2VDiBC5dGDOJfnQPRN+lK4YkaxmErIczutWNxiv4PwY61IAA UgeXEB8D7kcBlb1fGVsdmIJ+HXEYYCMbHDGyq250= Subject: FAILED: patch "[PATCH] mm/ptdump: take the memory hotplug lock inside" failed to apply to 6.1-stable tree To: anshuman.khandual@arm.com,agordeev@linux.ibm.com,akpm@linux-foundation.org,borntraeger@linux.ibm.com,catalin.marinas@arm.com,david@redhat.com,dev.jain@arm.com,gerald.schaefer@linux.ibm.com,gor@linux.ibm.com,hca@linux.ibm.com,palmer@dabbelt.com,paul.walmsley@sifive.com,ryan.roberts@arm.com,stable@vger.kernel.org,svens@linux.ibm.com,will@kernel.org Cc: From: Date: Mon, 18 Aug 2025 13:07:59 +0200 Message-ID: <2025081859-excess-willfully-0f01@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x 59305202c67fea50378dcad0cc199dbc13a0e99a # git commit -s git send-email --to '' --in-reply-to '2025081859-excess-willfully-0f01@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 59305202c67fea50378dcad0cc199dbc13a0e99a Mon Sep 17 00:00:00 2001 From: Anshuman Khandual Date: Fri, 20 Jun 2025 10:54:27 +0530 Subject: [PATCH] mm/ptdump: take the memory hotplug lock inside ptdump_walk_pgd() Memory hot remove unmaps and tears down various kernel page table regions as required. The ptdump code can race with concurrent modifications of the kernel page tables. When leaf entries are modified concurrently, the dump code may log stale or inconsistent information for a VA range, but this is otherwise not harmful. But when intermediate levels of kernel page table are freed, the dump code will continue to use memory that has been freed and potentially reallocated for another purpose. In such cases, the ptdump code may dereference bogus addresses, leading to a number of potential problems. To avoid the above mentioned race condition, platforms such as arm64, riscv and s390 take memory hotplug lock, while dumping kernel page table via the sysfs interface /sys/kernel/debug/kernel_page_tables. Similar race condition exists while checking for pages that might have been marked W+X via /sys/kernel/debug/kernel_page_tables/check_wx_pages which in turn calls ptdump_check_wx(). Instead of solving this race condition again, let's just move the memory hotplug lock inside generic ptdump_check_wx() which will benefit both the scenarios. Drop get_online_mems() and put_online_mems() combination from all existing platform ptdump code paths. Link: https://lkml.kernel.org/r/20250620052427.2092093-1-anshuman.khandual@arm.com Fixes: bbd6ec605c0f ("arm64/mm: Enable memory hot remove") Signed-off-by: Anshuman Khandual Acked-by: David Hildenbrand Reviewed-by: Dev Jain Acked-by: Alexander Gordeev [s390] Cc: Catalin Marinas Cc: Will Deacon Cc: Ryan Roberts Cc: Paul Walmsley Cc: Palmer Dabbelt Cc: Alexander Gordeev Cc: Gerald Schaefer Cc: Heiko Carstens Cc: Vasily Gorbik Cc: Christian Borntraeger Cc: Sven Schnelle Cc: Signed-off-by: Andrew Morton diff --git a/arch/arm64/mm/ptdump_debugfs.c b/arch/arm64/mm/ptdump_debugfs.c index 68bf1a125502..1e308328c079 100644 --- a/arch/arm64/mm/ptdump_debugfs.c +++ b/arch/arm64/mm/ptdump_debugfs.c @@ -1,6 +1,5 @@ // SPDX-License-Identifier: GPL-2.0 #include -#include #include #include @@ -9,9 +8,7 @@ static int ptdump_show(struct seq_file *m, void *v) { struct ptdump_info *info = m->private; - get_online_mems(); ptdump_walk(m, info); - put_online_mems(); return 0; } DEFINE_SHOW_ATTRIBUTE(ptdump); diff --git a/arch/riscv/mm/ptdump.c b/arch/riscv/mm/ptdump.c index 32922550a50a..3b51690cc876 100644 --- a/arch/riscv/mm/ptdump.c +++ b/arch/riscv/mm/ptdump.c @@ -6,7 +6,6 @@ #include #include #include -#include #include #include @@ -413,9 +412,7 @@ bool ptdump_check_wx(void) static int ptdump_show(struct seq_file *m, void *v) { - get_online_mems(); ptdump_walk(m, m->private); - put_online_mems(); return 0; } diff --git a/arch/s390/mm/dump_pagetables.c b/arch/s390/mm/dump_pagetables.c index ac604b176660..9af2aae0a515 100644 --- a/arch/s390/mm/dump_pagetables.c +++ b/arch/s390/mm/dump_pagetables.c @@ -247,11 +247,9 @@ static int ptdump_show(struct seq_file *m, void *v) .marker = markers, }; - get_online_mems(); mutex_lock(&cpa_mutex); ptdump_walk_pgd(&st.ptdump, &init_mm, NULL); mutex_unlock(&cpa_mutex); - put_online_mems(); return 0; } DEFINE_SHOW_ATTRIBUTE(ptdump); diff --git a/mm/ptdump.c b/mm/ptdump.c index 61a352aa12ed..b600c7f864b8 100644 --- a/mm/ptdump.c +++ b/mm/ptdump.c @@ -176,6 +176,7 @@ void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm, pgd_t *pgd) { const struct ptdump_range *range = st->range; + get_online_mems(); mmap_write_lock(mm); while (range->start != range->end) { walk_page_range_debug(mm, range->start, range->end, @@ -183,6 +184,7 @@ void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm, pgd_t *pgd) range++; } mmap_write_unlock(mm); + put_online_mems(); /* Flush out the last page */ st->note_page_flush(st);