From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 89C5647A0A1; Tue, 16 Jun 2026 17:09:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781629757; cv=none; b=sgirTSrGhPHIH4amhm7kag7/RrjI2N6d3BSZI5V3nt0lk9C+cxZCKbOPMVEgmPwm22IuVJHyw2XXYn3tn9K/t3TlkZLju2go0hUkJXeH7KwjxNmu+dwMM33Y/3Z8hB5ohQBlg0WEb9AZZgZssnlEyy6+AmycYw+JMlbFVon11mo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781629757; c=relaxed/simple; bh=kkuE/xUdTikCeJgzh/xcQHLqcxgKOC/zvFq0XziSE04=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=APeojr9hJWLA1nCyPphAMbVhsWoRdL5D1mIMqhdR7HckbFs8PaCJzz8FCsbwnq1MP/gEoaMdtGSpCqqnXXIQYB9XCMSNIeFzgoxGze7kdNApv0g9yv7mieJZSWoHgnkAxSlQHjvOqbFXmptOCK0t8Yo1KLMrF1kwNHMrLahKiz8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=uv6BqyBd; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="uv6BqyBd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 93D421F000E9; Tue, 16 Jun 2026 17:09:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1781629756; bh=jZ2o9Jdvc5z3DMcIGtSQDuQQAy1Mq+H0zzqwnp+FpHc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=uv6BqyBdQYbBnehc5W5iveGdwSj57GK2x/0N0/nshbFD/yM83fCcfZoNgckBxdklh ITf2DZlm8oXgdtcW1lBml0REjD0nrQe6duOxCULk8Ey0CGZeiDaniPyjvQc+V/I73M BWLRt63ys1xLrr8fX8ylulZVYVDpJY0tE0K1L0xE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, David Carlier , Muchun Song , David Hildenbrand , Mina Almasry , Oscar Salvador , yuehaibing , Andrew Morton Subject: [PATCH 6.6 347/452] mm/hugetlb: restore reservation on error in hugetlb folio copy paths Date: Tue, 16 Jun 2026 20:29:34 +0530 Message-ID: <20260616145135.465001191@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260616145117.796205997@linuxfoundation.org> References: <20260616145117.796205997@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Carlier commit 40c81856e622a9dc59294a90d169ac07ea25b0b0 upstream. Two sites in mm/hugetlb.c allocate a hugetlb folio via alloc_hugetlb_folio() (consuming a VMA reservation) and then call copy_user_large_folio(), which became int-returning in commit 1cb9dc4b475c ("mm: hwpoison: support recovery from HugePage copy-on-write faults") and can now fail (e.g. -EHWPOISON on a hwpoisoned source page). On the failure path, folio_put() restores the global hugetlb pool count through free_huge_folio(), but the per-VMA reservation map entry is left marked consumed: - hugetlb_mfill_atomic_pte() resubmission path (UFFDIO_COPY) - copy_hugetlb_page_range() fork-time CoW path when hugetlb_try_dup_anon_rmap() fails (rare: pinned hugetlb anon folio under fork) User-visible effect: on UFFDIO_COPY into a private hugetlb VMA where the resubmission copy fails, the reservation for that address is leaked from the VMA's reserve map. A subsequent fault at the same address takes the no-reservation path, and under hugetlb pool pressure the task is SIGBUSed at an address it had previously reserved. The fork-time CoW path leaks the same way in the child VMA's reserve map, though it requires the much rarer combination of pinned hugetlb anon page + hwpoisoned source. Add the missing restore_reserve_on_error() call before folio_put() on both error paths. Link: https://lore.kernel.org/20260520044912.6751-1-devnexen@gmail.com Fixes: 1cb9dc4b475c ("mm: hwpoison: support recovery from HugePage copy-on-write faults") Signed-off-by: David Carlier Reviewed-by: Muchun Song Cc: David Hildenbrand Cc: Mina Almasry Cc: Muchun Song Cc: Oscar Salvador Cc: yuehaibing Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- mm/hugetlb.c | 2 ++ 1 file changed, 2 insertions(+) --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -5174,6 +5174,7 @@ again: addr, dst_vma); folio_put(pte_folio); if (ret) { + restore_reserve_on_error(h, dst_vma, addr, new_folio); folio_put(new_folio); break; } @@ -6383,6 +6384,7 @@ int hugetlb_mfill_atomic_pte(pte_t *dst_ folio_put(*foliop); *foliop = NULL; if (ret) { + restore_reserve_on_error(h, dst_vma, dst_addr, folio); folio_put(folio); goto out; }