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=1794518523; b=SqQscFzKJ1SGfn2KsNwFXbwIffZ5S/ARv+DkAOvZ0mP+ZYtudt9q8V1OJNysn7ua4AAt Wm5e8W4kjTVRh2uDreGYZzDDr6BbtpvN7tYM8ynTNXDSNQW9n81M2o7oQn3S6/41IQxYQ SSQjHWvvhvKdu6b2idpUqibbIrj5QORhLHmvRk1rDgX/ZriV1CNoV71+hGABa1SRnnqB0 ZLukgPDHi3jrMxg2i+VzQTHAQHcIiJuJi6YRKsksbeGxCBIoOvi463vN5CcjotlOgU+QW FXcRyAwMkw4ANHQNNM6o5jv2WDP59vhj3nCs1V1y6yyAcZFMyXWACKlyWHopip9OsDw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794518523; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=yMug83nLKHxR9FXzvG9LAoy/tgkQAJH1i4Cd67PhO2Y=; b=mnRkdjyNK4LalNEwI/KaADVHgzV/H3D6tKlrlHomBhx81z7SsWO4tjHZR02ucB6RQKi6 HdggDcxnxXBwjVFQtq3T+O3fxkegxKrV70MXVnDuVpHXiW9eRJkltpp2892BMFl7DMPu2 GwpDnbM2ZhYCm/Zh/xCJrM6THExQcx3XqkYt0HzL7nv/feSp7DRQkNBpYiDrGL85eX+Rt xbZzxUrtYhhW1KkfxDaIjNDsnqaa0FlbcDOc3NwRPRm+vSt48FNP/vtQx6Dzc6txLQUXu z34EFs0drogppyGthQ5HPp6MLMCI/6u4gf7baOktuJvmAz0ov2TuUma3Dk948oq6Y7w== 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=S+KxyZL9; 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 7CCD1606A31C for ; Thu, 12 Nov 2026 21:22:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=S+KxyZL9 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 462F31F000C4; Thu, 12 Nov 2026 21:22:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794518523; bh=yMug83nLKHxR9FXzvG9LAoy/tgkQAJH1i4Cd67PhO2Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=S+KxyZL9sRFdCbm6Ab7exbH7ItXGZ4ztyBpu2kWHfXTfQxXcW89F2cx+zdoMteCz8 0rEIuhxjFkGOpRiOlHiMuIxkuvPJvhfZAGpgGAPbnxNxiTtLtDSFHkcBBkok4B0Kqj i8Afve+7SY1Z+hqI3qIRU6eJmHgzlNhGzyTnx44lqQf1I7Jw9Ocpdv+rhP2i7tUaYJ yy+zd0JxVRhLSmzGHL5Oa3TpbaCf7RP2h0KfMcHrq5pS5P05xR5itMnt8rMHLT0WJ4 kCE86zgVpBaaz5PNMr1W7NWGo3vHNRvv+4IPWy7EABWFxP7Wu54DLbrXlkLntxaI5a FFfpeeW7TRpgQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Josef Bacik , "Lorenzo Stoakes (ARM)" , Pedro Falcato , Muhammad Usama Anjum , Lance Yang , "David Hildenbrand (Arm)" , Sasha Levin Subject: [PATCH 5.10.y] mm/mremap: fix moving PUD leaves Date: Thu, 12 Nov 2026 16:22:00 -0500 Message-ID: <20261112212105.3778698-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261109202811-failed-5.10-440c8779757f@kernel.org> References: <20261109202811-failed-5.10-440c8779757f@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Josef Bacik [ Upstream commit 440c8779757f09f290770b1d361dc1516a9d0b3e ] 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 Link: https://patch.msgid.link/20261031-fixes_core-v3-32-d6437171ecc3@kernel.org Reviewed-by: Lance Yang Signed-off-by: David Hildenbrand (Arm) [ sashal: applied split_huge_pud() directly in get_old_pmd() because get_old_pud() and whole-PUD move support are absent ] Signed-off-by: Sasha Levin --- mm/mremap.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/mm/mremap.c b/mm/mremap.c index 79beead5af830..eca03a9789049 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -30,8 +30,9 @@ #include "internal.h" -static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr) +static pmd_t *get_old_pmd(struct vm_area_struct *vma, unsigned long addr) { + struct mm_struct *mm = vma->vm_mm; pgd_t *pgd; p4d_t *p4d; pud_t *pud; @@ -46,6 +47,7 @@ static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr) return NULL; pud = pud_offset(p4d, addr); + split_huge_pud(vma, pud, addr); if (pud_none_or_clear_bad(pud)) return NULL; @@ -280,7 +282,7 @@ unsigned long move_page_tables(struct vm_area_struct *vma, next = (new_addr + PMD_SIZE) & PMD_MASK; if (extent > next - new_addr) extent = next - new_addr; - old_pmd = get_old_pmd(vma->vm_mm, old_addr); + old_pmd = get_old_pmd(vma, old_addr); if (!old_pmd) continue; new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr); -- 2.53.0