From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754143Ab3KBCvM (ORCPT ); Fri, 1 Nov 2013 22:51:12 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:48486 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753759Ab3KBCvK (ORCPT ); Fri, 1 Nov 2013 22:51:10 -0400 Message-ID: <5274688D.7050902@oracle.com> Date: Sat, 02 Nov 2013 10:50:53 +0800 From: Bob Liu User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130308 Thunderbird/17.0.4 MIME-Version: 1.0 To: Olav Haugan CC: Minchan Kim , sjenning@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: zram/zsmalloc issues in very low memory conditions References: <526844E6.1080307@codeaurora.org> <20131025091924.GA4970@gmail.com> <52744E8F.3040405@codeaurora.org> In-Reply-To: <52744E8F.3040405@codeaurora.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Source-IP: acsinet22.oracle.com [141.146.126.238] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Olav, On 11/02/2013 08:59 AM, Olav Haugan wrote: > > I tried the above suggestion but it does not seem to have any noticeable > impact. The system is still trying to swap out at a very high rate after > zram reported failure to swap out. The error logging is actually so much > that my system crashed due to excessive logging (we have a watchdog that > is not getting pet because the kernel is busy logging kernel messages). > I have a question that why the low memory killer didn't get triggered in this situation? Is it possible to set the LMK a bit more aggressive? > There isn't anything that can be set to tell the fs layer to back off > completely for a while (congestion control)? > The other way I think might fix your issue is the same as your mentioned in your previous email. Set the congested bit for swap device also. Like: diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c index 91d94b5..c4fc63e 100644 --- a/drivers/staging/zram/zram_drv.c +++ b/drivers/staging/zram/zram_drv.c @@ -474,6 +474,7 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, if (!handle) { pr_info("Error allocating memory for compressed page: %u, size=%zu\n", index, clen); + blk_set_queue_congested(zram->disk->queue, BLK_RW_ASYNC); ret = -ENOMEM; goto out; } diff --git a/mm/vmscan.c b/mm/vmscan.c index 8ed1b77..1c790ee 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -394,8 +394,6 @@ static inline int is_page_cache_freeable(struct page *page) static int may_write_to_queue(struct backing_dev_info *bdi, struct scan_control *sc) { - if (current->flags & PF_SWAPWRITE) - return 1; -------------------------------------------------------------- For the update of the congested state of zram, I think you can clear it from use space eg. after LMK triggered and reclaimed some memory. Of course this depends on zram driver to export a sysfs node like "/sys/block/zram0/clear_congested". -- Regards, -Bob