From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laura Abbott Subject: Re: CMA page migration failure due to buffers on bh_lru Date: Fri, 31 Aug 2012 13:46:54 -0700 Message-ID: <504122BE.8080706@codeaurora.org> References: <503EBBD6.5080504@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from wolverine01.qualcomm.com ([199.106.114.254]:26947 "EHLO wolverine01.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751855Ab2HaUrL (ORCPT ); Fri, 31 Aug 2012 16:47:11 -0400 In-Reply-To: <503EBBD6.5080504@codeaurora.org> Sender: linux-arm-msm-owner@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org To: linux-fsdevel@vger.kernel.org, Marek Szyprowski Cc: linaro-mm-sig@lists.linaro.org, "linux-arm-msm@vger.kernel.org" , linux-kernel@vger.kernel.org, "linux-arm-kernel@lists.infradead.org" On 8/29/2012 6:03 PM, Laura Abbott wrote: > My quick and dirty workaround for testing is to remove the GFP_MOVABLE > flag from find_or_create_page but this seems significantly less than > optimal. Ideally, it seems like the buffers should be evicted from the > LRU when trying to drop (expand on invalid_bh_lru?) but I'm not familiar > enough with the code path to know if this is a good approach. > > Any suggestions/feedback is appreciated. Thanks. > > Laura I came up with what I think is a reasonable fix to this. Feedback is appreciated. Thanks. Laura 8<--- diff --git a/fs/buffer.c b/fs/buffer.c index ad5938c..daa0c3d 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -1399,12 +1399,49 @@ static bool has_bh_in_lru(int cpu, void *dummy) return 0; } +static void __evict_bh_lru(void *arg) +{ + struct bh_lru *b = &get_cpu_var(bh_lrus); + struct buffer_head *bh = arg; + int i; + + for (i = 0; i < BH_LRU_SIZE; i++) { + if (b->bhs[i] == bh) { + brelse(b->bhs[i]); + b->bhs[i] = NULL; + goto out; + } + } +out: + put_cpu_var(bh_lrus); +} + +static bool bh_exists_in_lru(int cpu, void *arg) +{ + struct bh_lru *b = per_cpu_ptr(&bh_lrus, cpu); + struct buffer_head *bh = arg; + int i; + + for (i = 0; i < BH_LRU_SIZE; i++) { + if (b->bhs[i] == bh) + return 1; + } + + return 0; + +} void invalidate_bh_lrus(void) { on_each_cpu_cond(has_bh_in_lru, invalidate_bh_lru, NULL, 1, GFP_KERNEL); } EXPORT_SYMBOL_GPL(invalidate_bh_lrus); +void evict_bh_lrus(struct buffer_head *bh) +{ + on_each_cpu_cond(bh_exists_in_lru, __evict_bh_lru, bh, 1, GFP_ATOMIC); +} +EXPORT_SYMBOL_GPL(evict_bh_lrus); + void set_bh_page(struct buffer_head *bh, struct page *page, unsigned long offset) { @@ -3052,6 +3089,7 @@ drop_buffers(struct page *page, struct buffer_head **buffers_to_free) bh = head; do { + evict_bh_lrus(bh); if (buffer_write_io_error(bh) && page->mapping) set_bit(AS_EIO, &page->mapping->flags); if (buffer_busy(bh)) -- -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation