From patchwork Tue Apr 9 19:22:51 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 13623163 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 3E8521586F2 for ; Tue, 9 Apr 2024 19:25:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712690720; cv=none; b=LP4wWXFQfUHxbqMVYiAHc5yPkXWZmR51ofwrfbIEr/CJO+rNiPtxrytK2wB/SsN7rHfAINVC98T8pgRR82PH/TGTw4hA/hVqH7VFP+X3cB3Mu5CyglXyy9mInklyNG+LzTbNBwznu8DXo56buxPnRP/NHN5vLNSSIJtbyOB94C0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712690720; c=relaxed/simple; bh=U2FYI/zDEFEDbvVedqLdfE5jV/TmoU4yobw78EI2s0U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=N2twyFE6XMGVF+LabeBnJ/xt51xcpftPayfe/BZB7ZHBbUumHEI1reb75hi+nEQQVPUEAdwu3Hp+N3bUGV51YHZsnn4dBWT8pILS8OzF6lGFK8KdiJsntikA+bO133SAzCwnOuqDy7KN49aietp49zI583CZGBkVSkRWZYpOKv0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=A5/9zM/r; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="A5/9zM/r" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1712690718; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=l2g8VbuF2c0rw+gA2SjXZjA9kizkfkgdJ7YGUNRZUqA=; b=A5/9zM/rM7JBKoNLt24FNgKWH++cfxED7fGDqn/iJdK4yEgqQcPq9p26ewUj/RhN9Lpzmu i1YIS8Jh0jmhQ/ApPJ1Pmi3GP4so/XtM4oygFSQG8MHWGUj9wL7sOxvKSEMSdSxjzt35qC P4wjhcLth2ixmeZ6HNcLf5S6uxv0hF8= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-61-9JpVPi_eMcaHlYj18Lcjpg-1; Tue, 09 Apr 2024 15:25:10 -0400 X-MC-Unique: 9JpVPi_eMcaHlYj18Lcjpg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 9AB78806625; Tue, 9 Apr 2024 19:25:08 +0000 (UTC) Received: from t14s.redhat.com (unknown [10.39.192.106]) by smtp.corp.redhat.com (Postfix) with ESMTP id BCB3B40B4980; Tue, 9 Apr 2024 19:24:56 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linux-doc@vger.kernel.org, cgroups@vger.kernel.org, linux-sh@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, David Hildenbrand , Andrew Morton , "Matthew Wilcox (Oracle)" , Peter Xu , Ryan Roberts , Yin Fengwei , Yang Shi , Zi Yan , Jonathan Corbet , Hugh Dickins , Yoshinori Sato , Rich Felker , John Paul Adrian Glaubitz , Chris Zankel , Max Filippov , Muchun Song , Miaohe Lin , Naoya Horiguchi , Richard Chang Subject: [PATCH v1 08/18] mm/huge_memory: use folio_mapcount() in zap_huge_pmd() sanity check Date: Tue, 9 Apr 2024 21:22:51 +0200 Message-ID: <20240409192301.907377-9-david@redhat.com> In-Reply-To: <20240409192301.907377-1-david@redhat.com> References: <20240409192301.907377-1-david@redhat.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.2 We want to limit the use of page_mapcount() to the places where it is absolutely necessary. Let's similarly check for folio_mapcount() underflows instead of page_mapcount() underflows like we do in zap_present_folio_ptes() now. Instead of the VM_BUG_ON(), we should actually be doing something like print_bad_pte(). For now, let's keep it simple and use WARN_ON_ONCE(), performing that check independently of DEBUG_VM. Signed-off-by: David Hildenbrand --- mm/huge_memory.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index d8d2ed80b0bf..68ac27d229ef 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1851,7 +1851,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, folio = page_folio(page); folio_remove_rmap_pmd(folio, page, vma); - VM_BUG_ON_PAGE(page_mapcount(page) < 0, page); + WARN_ON_ONCE(folio_mapcount(folio) < 0); VM_BUG_ON_PAGE(!PageHead(page), page); } else if (thp_migration_supported()) { swp_entry_t entry;