From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793440115; b=xXR8A4ukLauBs8DLsveT/MCOznGW/PM9bJh4gP13JKSpWFK1GoPcuGDkKWIbcW0hnHj8 vmXQlPaOwXwLmz+gBwPv18zZP23PVPJ+fxt2Ap4tJtfxAlnijErloUxuMl9Nug35t3jLk K4hoLqa4JKcIjyAF5oeMYI63H9RgEsvDdGWJoCauuMg8gP+cFNgWakuk7vwSnS4ffFzVn OowdJzktzBwzTqj8QBWpjSQoVQwt4/7eU8+NheNCvPOtN44ZNn99nnr03XXoaHawUV+2x vhIwJACHLKuLTg1byUeuGINceSr9vWQrXWDTDO7WuofUK471QW+Ml9P8OI8XEtluasw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793440115; h=Received:DKIM-Signature:From:Date:Subject:MIME-Version:Content-Type: Content-Transfer-Encoding:Message-Id:References:In-Reply-To:To:Cc: X-Mailer:X-Developer-Signature:X-Developer-Key; bh=YHe1ZtAJayVrktC+oIcIv9hMCqgNETJjHBAQ4hVj50U=; b=cBx7mUiCl3o4vQ7Mj7munaNaafjQynZDt1NA7/oKtziiklqcBB4gRka23b7MePfbKwbW zrBNNEZwvkMpibFiagpJBpIagId3pNXBwhcrotPXfuLLb4Leq8a1GVPhJhe69BlYf/afy LdEe2PlnhOv5231bzEo/gaxJjfHng7Op8w22ZIcFyYznbXZkzQeZzB1kcZTCvuUwhA7Z/ ZyxctGmC9AdxUTYv9J61H+9lpglrO5tgOe7bZ2nSXrNMKA1TU+mqfLpHVGFrfpSkFi0qt P1kup8BKUcjdsJz+JxCVVBqCDOXpdVH1eK4hQEglT3bRIF/owal9u/RNlsjUSu9ctog== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=c680gRXN; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BD83E606A31C; Sat, 31 Oct 2026 09:48:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=c680gRXN Received: by smtp.kernel.org (Postfix) with ESMTPSA id 61D8F1F000C1; Sat, 31 Oct 2026 09:48:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793440114; bh=YHe1ZtAJayVrktC+oIcIv9hMCqgNETJjHBAQ4hVj50U=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=c680gRXN1S8i2NWT11+qqfJhCsH6sZm3Lgl8IeH2hJ2aV1qzLZQtIe8ZB/S0Y8M4u fN/ZfkmGKaWRQLUfNH59CwiDPnl5tXhgo8CD2EYJIAEsLtjBm4rRe8GJm38fmOmjuL FFXv6XLkluWIuC2aGtTKDBtJbzSA3zIsT4UjaArwgZp431mebT1HiG8P+W6A5AvJ1j xyMsVE2U0KpbxJPGXkloi1TT6aBkxHFddiVm/NixvrDnNSFKwp2dWiy9scRGfSCgIf 5wyb9blmNExkoGtL0VUhhBQtgKS3NSi9uiCInnqcR5ifvCRN0AukPxZBsAGRbFB6tI Ngi7/1neI9RLQ== From: "David Hildenbrand (Arm)" Date: Sat, 31 Oct 2026 10:40:01 +0100 Subject: [PATCH v3 32/47] mm/mremap: fix moving PUD leaves 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: <20261031-fixes_core-v3-32-d6437171ecc3@kernel.org> References: <20261031-fixes_core-v3-0-d6437171ecc3@kernel.org> In-Reply-To: <20261031-fixes_core-v3-0-d6437171ecc3@kernel.org> To: Andrew Morton , Johannes Weiner , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kees Cook , Peter Zijlstra , Jann Horn , Pedro Falcato , Hugh Dickins , Pasha Tatashin , Pratyush Yadav , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Lance Yang , Rik van Riel , Harry Yoo , Alistair Popple , Nico Pache , Ryan Roberts , Dev Jain , Usama Arif , Kiryl Shutsemau , Matthew Brost , John Hubbard , Peter Xu , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Oscar Salvador , Minchan Kim , Muchun Song , Xu Xin , Chengming Zhou , Chris Li , Kemeng Shi , Nhat Pham , Youngjun Park , Gregory Price , Joshua Hahn , Rakie Kim , Ying Huang , Jason Gunthorpe Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, Josef Bacik , stable@vger.kernel.org, Muhammad Usama Anjum , "David Hildenbrand (Arm)" X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2279; i=david@kernel.org; h=from:subject:message-id; bh=yDC0RTefMrDLgTK9qV0M/e1RR0BKaMeuZ5BjV9QtmSQ=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLKebs8MndYZbbZZdftFjSuZ9ms2y146fHvrmjOOU3Uzv mccUXBe0lHKwiDGwSArpsgSFHzf4OXLdbXVbnzMMHNYmUCGMHBxCsBEjn5m+KdRKHbDdvvW6CkH kuZtmpttl3HlxIzcUG8tAf0dp2/k94YyMpwP/WSvviF49lHx24JPNvidbp4Xsbt7e4hGjZWt9ek L75gA X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A From: Josef Bacik pud_none_or_clear_bad() only really works on page tables. PUD leaves confuse the check and make us clear the page table entry and print a warning. Since commit aed877c2b4257 ("device/dax: properly refcount device dax pages when mapping"), this also leaks device-DAX folio references, mapcounts and RSS accounting, resulting in "Bad rss-counter state" warnings on exit. Allow PUD leaves in get_old_pud(). If a PUD leaf cannot be moved as a whole or the move fails, split it. This unmaps it with proper accounting instead of treating the leaf entry as a PMD table. Keep using pud_trans_huge() for now, in the future this code should be cleaned up to just check for PUD leaves. Fix generated by an LLM and sent by Josef Bacik in private. Fixes: a00cc7d9dd93 ("mm, x86: add support for PUD-sized transparent hugepages") Cc: stable@vger.kernel.org Signed-off-by: Josef Bacik Reviewed-by: Lorenzo Stoakes (ARM) [ david: fallthrough after splitting ] Reviewed-by: Pedro Falcato Tested-by: Muhammad Usama Anjum Signed-off-by: David Hildenbrand (Arm) --- mm/mremap.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/mm/mremap.c b/mm/mremap.c index 91f0865f6aeea..1237718848f5c 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -87,7 +87,7 @@ static pud_t *get_old_pud(struct mm_struct *mm, unsigned long addr) return NULL; pud = pud_offset(p4d, addr); - if (pud_none_or_clear_bad(pud)) + if (!pud_trans_huge(*pud) && pud_none_or_clear_bad(pud)) return NULL; return pud; @@ -847,11 +847,10 @@ unsigned long move_page_tables(struct pagetable_move_control *pmc) if (!new_pud) break; if (pud_trans_huge(*old_pud)) { - if (extent == HPAGE_PUD_SIZE) { - move_pgt_entry(pmc, HPAGE_PUD, old_pud, new_pud); - /* We ignore and continue on error? */ + if (extent == HPAGE_PUD_SIZE && + move_pgt_entry(pmc, HPAGE_PUD, old_pud, new_pud)) continue; - } + split_huge_pud(pmc->old, old_pud, pmc->old_addr); } else if (IS_ENABLED(CONFIG_HAVE_MOVE_PUD) && extent == PUD_SIZE) { if (move_pgt_entry(pmc, NORMAL_PUD, old_pud, new_pud)) continue; -- 2.43.0