From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qg0-f49.google.com (mail-qg0-f49.google.com [209.85.192.49]) by kanga.kvack.org (Postfix) with ESMTP id B996A6B0032 for ; Sun, 8 Mar 2015 16:38:41 -0400 (EDT) Received: by qgfh3 with SMTP id h3so24227686qgf.13 for ; Sun, 08 Mar 2015 13:38:41 -0700 (PDT) Received: from mail-qg0-x232.google.com (mail-qg0-x232.google.com. [2607:f8b0:400d:c04::232]) by mx.google.com with ESMTPS id f135si1967080qhe.122.2015.03.08.13.38.40 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 08 Mar 2015 13:38:41 -0700 (PDT) Received: by qgdz60 with SMTP id z60so24271457qgd.5 for ; Sun, 08 Mar 2015 13:38:40 -0700 (PDT) Date: Sun, 8 Mar 2015 16:38:39 -0400 From: Michal Hocko Subject: Re: mm: hangs in free_pages_prepare Message-ID: <20150308203838.GA10442@dhcp22.suse.cz> References: <54FB4590.20102@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <54FB4590.20102@oracle.com> Sender: owner-linux-mm@kvack.org List-ID: To: Sasha Levin Cc: "linux-mm@kvack.org" , "akpm >> Andrew Morton" On Sat 07-03-15 13:38:08, Sasha Levin wrote: [...] > [ 1573.730097] ? kasan_free_pages (mm/kasan/kasan.c:301) > [ 1573.788680] free_pages_prepare (mm/page_alloc.c:791) > [ 1573.788680] ? free_hot_cold_page (./arch/x86/include/asm/paravirt.h:809 (discriminator 2) mm/page_alloc.c:1579 (discriminator 2)) > [ 1573.788680] free_hot_cold_page (mm/page_alloc.c:1543) > [ 1573.788680] __free_pages (mm/page_alloc.c:2957) > [ 1573.788680] ? __vunmap (mm/vmalloc.c:1460 (discriminator 2)) > [ 1573.788680] __vunmap (mm/vmalloc.c:1460 (discriminator 2)) __vunmap is doing: for (i = 0; i < area->nr_pages; i++) { struct page *page = area->pages[i]; BUG_ON(!page); __free_page(page); } is it possible that nr_pages is a huge number (a large vmalloc area)? I do not see any cond_resched down __free_page path at least. vfree delayes the call to workqueue when called from irq context and vunmap is marked as might_sleep). So to me it looks like it would be safe. Something for vmalloc familiar people, though. Anyway, the loop seems to be there since ages so I guess somebody just started calling vmalloc for huge areas recently so it shown up. -- Michal Hocko SUSE Labs -- 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/ . Don't email: email@kvack.org