From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wj0-f199.google.com (mail-wj0-f199.google.com [209.85.210.199]) by kanga.kvack.org (Postfix) with ESMTP id AFCF36B0069 for ; Thu, 29 Dec 2016 04:14:53 -0500 (EST) Received: by mail-wj0-f199.google.com with SMTP id iq1so32226914wjb.1 for ; Thu, 29 Dec 2016 01:14:53 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id i202si53518417wmd.36.2016.12.29.01.14.52 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 29 Dec 2016 01:14:52 -0800 (PST) Date: Thu, 29 Dec 2016 10:14:49 +0100 From: Michal Hocko Subject: Re: [PATCH] mm: cma: print allocation failure reason and bitmap status Message-ID: <20161229091449.GG29208@dhcp22.suse.cz> References: <1482978482-14007-1-git-send-email-jaewon31.kim@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1482978482-14007-1-git-send-email-jaewon31.kim@samsung.com> Sender: owner-linux-mm@kvack.org List-ID: To: Jaewon Kim Cc: gregkh@linuxfoundation.org, akpm@linux-foundation.org, labbott@redhat.com, mina86@mina86.com, m.szyprowski@samsung.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, jaewon31.kim@gmail.com On Thu 29-12-16 11:28:02, Jaewon Kim wrote: > There are many reasons of CMA allocation failure such as EBUSY, ENOMEM, EINTR. > This patch prints the error value and bitmap status to know available pages > regarding fragmentation. > > This is an ENOMEM example with this patch. > [ 11.616321] [2: Binder:711_1: 740] cma: cma_alloc: alloc failed, req-size: 256 pages, ret: -12 > [ 11.616365] [2: Binder:711_1: 740] number of available pages: 4+7+7+8+38+166+127=>357 pages, total: 2048 pages Could you be more specific why this part is useful? > Signed-off-by: Jaewon Kim > --- > mm/cma.c | 29 ++++++++++++++++++++++++++++- > 1 file changed, 28 insertions(+), 1 deletion(-) > > diff --git a/mm/cma.c b/mm/cma.c > index c960459..535aa39 100644 > --- a/mm/cma.c > +++ b/mm/cma.c > @@ -369,7 +369,7 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align) > unsigned long start = 0; > unsigned long bitmap_maxno, bitmap_no, bitmap_count; > struct page *page = NULL; > - int ret; > + int ret = -ENOMEM; > > if (!cma || !cma->count) > return NULL; > @@ -427,6 +427,33 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align) > trace_cma_alloc(pfn, page, count, align); > > pr_debug("%s(): returned %p\n", __func__, page); > + > + if (ret != 0) { > + unsigned int nr, nr_total = 0; > + unsigned long next_set_bit; > + > + pr_info("%s: alloc failed, req-size: %zu pages, ret: %d\n", > + __func__, count, ret); > + mutex_lock(&cma->lock); > + printk("number of available pages: "); > + start = 0; > + for (;;) { > + bitmap_no = find_next_zero_bit(cma->bitmap, cma->count, start); > + next_set_bit = find_next_bit(cma->bitmap, cma->count, bitmap_no); > + nr = next_set_bit - bitmap_no; > + if (bitmap_no >= cma->count) > + break; > + if (nr_total == 0) > + printk("%u", nr); > + else > + printk("+%u", nr); > + nr_total += nr; > + start = bitmap_no + nr; > + } > + printk("=>%u pages, total: %lu pages\n", nr_total, cma->count); > + mutex_unlock(&cma->lock); > + } > + > return page; > } > > -- > 1.9.1 > > -- > 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 -- 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