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[94.245.46.61]) by smtp.gmail.com with ESMTPSA id s15sm1376039ljj.14.2021.11.23.11.01.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 23 Nov 2021 11:01:53 -0800 (PST) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Tue, 23 Nov 2021 20:01:50 +0100 To: Michal Hocko Cc: Andrew Morton , Dave Chinner , Neil Brown , Christoph Hellwig , Uladzislau Rezki , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, LKML , Ilya Dryomov , Jeff Layton , Michal Hocko Subject: Re: [PATCH v2 2/4] mm/vmalloc: add support for __GFP_NOFAIL Message-ID: References: <20211122153233.9924-1-mhocko@kernel.org> <20211122153233.9924-3-mhocko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211122153233.9924-3-mhocko@kernel.org> X-Stat-Signature: epecospbscc1m1wmype3sfcpepeo7xjd Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=pcfaLKAc; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf03.hostedemail.com: domain of urezki@gmail.com designates 209.85.208.174 as permitted sender) smtp.mailfrom=urezki@gmail.com X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 228963001A09 X-HE-Tag: 1637694114-463702 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Nov 22, 2021 at 04:32:31PM +0100, Michal Hocko wrote: > From: Michal Hocko > > Dave Chinner has mentioned that some of the xfs code would benefit from > kvmalloc support for __GFP_NOFAIL because they have allocations that > cannot fail and they do not fit into a single page. > > The large part of the vmalloc implementation already complies with the > given gfp flags so there is no work for those to be done. The area > and page table allocations are an exception to that. Implement a retry > loop for those. > > Add a short sleep before retrying. 1 jiffy is a completely random > timeout. Ideally the retry would wait for an explicit event - e.g. > a change to the vmalloc space change if the failure was caused by > the space fragmentation or depletion. But there are multiple different > reasons to retry and this could become much more complex. Keep the retry > simple for now and just sleep to prevent from hogging CPUs. > > Signed-off-by: Michal Hocko > --- > mm/vmalloc.c | 22 +++++++++++++++++----- > 1 file changed, 17 insertions(+), 5 deletions(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 17ca7001de1f..b6aed4f94a85 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -2844,6 +2844,8 @@ vm_area_alloc_pages(gfp_t gfp, int nid, > * more permissive. > */ > if (!order) { > + gfp_t bulk_gfp = gfp & ~__GFP_NOFAIL; > + > while (nr_allocated < nr_pages) { > unsigned int nr, nr_pages_request; > > @@ -2861,12 +2863,12 @@ vm_area_alloc_pages(gfp_t gfp, int nid, > * but mempolcy want to alloc memory by interleaving. > */ > if (IS_ENABLED(CONFIG_NUMA) && nid == NUMA_NO_NODE) > - nr = alloc_pages_bulk_array_mempolicy(gfp, > + nr = alloc_pages_bulk_array_mempolicy(bulk_gfp, > nr_pages_request, > pages + nr_allocated); > > else > - nr = alloc_pages_bulk_array_node(gfp, nid, > + nr = alloc_pages_bulk_array_node(bulk_gfp, nid, > nr_pages_request, > pages + nr_allocated); > > @@ -2921,6 +2923,7 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask, > { > const gfp_t nested_gfp = (gfp_mask & GFP_RECLAIM_MASK) | __GFP_ZERO; > const gfp_t orig_gfp_mask = gfp_mask; > + bool nofail = gfp_mask & __GFP_NOFAIL; > unsigned long addr = (unsigned long)area->addr; > unsigned long size = get_vm_area_size(area); > unsigned long array_size; > @@ -2978,8 +2981,12 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask, > else if ((gfp_mask & (__GFP_FS | __GFP_IO)) == 0) > flags = memalloc_noio_save(); > > - ret = vmap_pages_range(addr, addr + size, prot, area->pages, > + do { > + ret = vmap_pages_range(addr, addr + size, prot, area->pages, > page_shift); > + if (nofail && (ret < 0)) > + schedule_timeout_uninterruptible(1); > + } while (nofail && (ret < 0)); > > if ((gfp_mask & (__GFP_FS | __GFP_IO)) == __GFP_IO) > memalloc_nofs_restore(flags); > @@ -3074,9 +3081,14 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align, > VM_UNINITIALIZED | vm_flags, start, end, node, > gfp_mask, caller); > if (!area) { > + bool nofail = gfp_mask & __GFP_NOFAIL; > warn_alloc(gfp_mask, NULL, > - "vmalloc error: size %lu, vm_struct allocation failed", > - real_size); > + "vmalloc error: size %lu, vm_struct allocation failed%s", > + real_size, (nofail) ? ". Retrying." : ""); > + if (nofail) { > + schedule_timeout_uninterruptible(1); > + goto again; > + } > goto fail; > } > > -- > 2.30.2 > I have raised two concerns in our previous discussion about this change, well that is sad... -- Vlad Rezki