From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1lwHmv-00CmbR-I6 for kexec@lists.infradead.org; Thu, 24 Jun 2021 05:20:30 +0000 From: Baoquan He Subject: [PATCH 2/2] dma-pool: allow user to disable atomic pool Date: Thu, 24 Jun 2021 13:20:10 +0800 Message-Id: <20210624052010.5676-3-bhe@redhat.com> In-Reply-To: <20210624052010.5676-1-bhe@redhat.com> References: <20210624052010.5676-1-bhe@redhat.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, x86@kernel.org, rientjes@google.com, rppt@linux.ibm.com, thomas.lendacky@amd.com, brijesh.singh@amd.com, kexec@lists.infradead.org, bhe@redhat.com In the current code, three atomic memory pools are provided, atomic_pool_kernel, atomic_pool_dma, atomic_pool_dma32, initialized with flag GFP_KERNEL, GFP_KERNEL|GFP_DMA, GFP_KERNEL|GFP_DMA32. And they are always enabled, even though 'coherent_pool=0' is specified in kernel command line. In some cases, atomic pool may not be needed. And worse, it even will cause problem. E.g in kdump kernel of x86_64, it will cause OOM for atomic_pool_dma initialization. Because there isn't available memory for buddy allocatory in DMA zone of kdump kernel since commit f1d4d47c5851 ("x86/setup: Always reserve the first 1M of RAM"). The OOM will cause panic if panic_on_oom is added into kdump kernel. So change code to adjust the existing coherent_pool to allow user to disable atomic pool by specifying 'coherent_pool=0'. Signed-off-by: Baoquan He --- kernel/dma/pool.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c index 5f84e6cdb78e..5a85804b5beb 100644 --- a/kernel/dma/pool.c +++ b/kernel/dma/pool.c @@ -21,7 +21,7 @@ static struct gen_pool *atomic_pool_kernel __ro_after_init; static unsigned long pool_size_kernel; /* Size can be defined by the coherent_pool command line */ -static size_t atomic_pool_size; +static unsigned long atomic_pool_size = -1; /* Dynamic background expansion when the atomic pool is near capacity */ static struct work_struct atomic_pool_work; @@ -188,11 +188,14 @@ static int __init dma_atomic_pool_init(void) { int ret = 0; + if (!atomic_pool_size) + return 0; + /* * If coherent_pool was not used on the command line, default the pool * sizes to 128KB per 1GB of memory, min 128KB, max MAX_ORDER-1. */ - if (!atomic_pool_size) { + if (atomic_pool_size == -1) { unsigned long pages = totalram_pages() / (SZ_1G / SZ_128K); pages = min_t(unsigned long, pages, MAX_ORDER_NR_PAGES); atomic_pool_size = max_t(size_t, pages << PAGE_SHIFT, SZ_128K); -- 2.17.2 _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec