From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta8.messagelabs.com (mail6.bemta8.messagelabs.com [216.82.243.55]) by kanga.kvack.org (Postfix) with ESMTP id 38E756B0109 for ; Sun, 5 Jun 2011 09:43:20 -0400 (EDT) Date: Sun, 5 Jun 2011 14:43:17 +0100 From: Al Viro Subject: ENOSPC returned by handle_mm_fault() Message-ID: <20110605134317.GF11521@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: Mel Gorman , linux-kernel@vger.kernel.org When alloc_huge_page() runs afoul of quota, it returns ERR_PTR(-ENOSPC). Callers do not expect that - hugetlb_cow() returns ENOSPC if it gets that and so does hugetlb_no_page(). Eventually the thing propagates back to hugetlb_fault() and is returned by it. Callers of hugetlb_fault() clearly expect a bitmap of VM_... and not something from errno.h: one place is ret = hugetlb_fault(mm, vma, vaddr, (flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0); spin_lock(&mm->page_table_lock); if (!(ret & VM_FAULT_ERROR)) continue; and another is handle_mm_fault(), which ends up returning ENOSPC and *its* callers are definitely not ready to deal with that. ENOSPC is 28, i.e. VM_FAULT_MAJOR | VM_FAULT_WRITE | VM_FAULT_HWPOISON; it's also theoretically possible to get ENOMEM if region_chg() ends up hitting nrg = kmalloc(sizeof(*nrg), GFP_KERNEL); if (!nrg) return -ENOMEM; region_chg() <- vma_needs_reservation() <- alloc_huge_page() and from that point as with ENOSPC. ENOMEM is 12, i.e. VM_FAULT_MAJOR | VM_FAULT_WRITE... Am I right assuming that we want VM_FAULT_OOM in both cases? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org