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Message-ID: <202511252040.Jny2Yxxn-lkp@intel.com>
Date: Tue, 25 Nov 2025 20:17:22 +0800
From: kernel test robot <lkp@...el.com>
To: Steven Rostedt <rostedt@...dmis.org>,
LKML <linux-kernel@...r.kernel.org>,
Linux Trace Kernel <linux-trace-kernel@...r.kernel.org>
Cc: oe-kbuild-all@...ts.linux.dev, Masami Hiramatsu <mhiramat@...nel.org>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Subject: Re: [PATCH] ring-buffer: Add helper functions for allocations
Hi Steven,
kernel test robot noticed the following build warnings:
[auto build test WARNING on trace/for-next]
[also build test WARNING on linus/master v6.18-rc7 next-20251125]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Steven-Rostedt/ring-buffer-Add-helper-functions-for-allocations/20251125-031044
base: https://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace for-next
patch link: https://lore.kernel.org/r/20251124140906.71a2abf6%40gandalf.local.home
patch subject: [PATCH] ring-buffer: Add helper functions for allocations
config: x86_64-defconfig (https://download.01.org/0day-ci/archive/20251125/202511252040.Jny2Yxxn-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251125/202511252040.Jny2Yxxn-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202511252040.Jny2Yxxn-lkp@intel.com/
All warnings (new ones prefixed by >>):
kernel/trace/ring_buffer.c: In function '__rb_allocate_pages':
>> kernel/trace/ring_buffer.c:2279:30: warning: unused variable 'page' [-Wunused-variable]
2279 | struct page *page;
| ^~~~
>> kernel/trace/ring_buffer.c:2242:15: warning: variable 'mflags' set but not used [-Wunused-but-set-variable]
2242 | gfp_t mflags;
| ^~~~~~
kernel/trace/ring_buffer.c: In function 'rb_allocate_cpu_buffer':
kernel/trace/ring_buffer.c:2362:22: warning: unused variable 'page' [-Wunused-variable]
2362 | struct page *page;
| ^~~~
kernel/trace/ring_buffer.c: In function 'ring_buffer_alloc_read_page':
kernel/trace/ring_buffer.c:6493:22: warning: unused variable 'page' [-Wunused-variable]
6493 | struct page *page;
| ^~~~
vim +/page +2279 kernel/trace/ring_buffer.c
c76883f18e59b7 Steven Rostedt (Google 2024-06-12 2234)
74e2afc6df5782 Qiujun Huang 2020-10-15 2235 static int __rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer,
74e2afc6df5782 Qiujun Huang 2020-10-15 2236 long nr_pages, struct list_head *pages)
7a8e76a3829f10 Steven Rostedt 2008-09-29 2237 {
be68d63a139bd4 Steven Rostedt (Google 2024-06-12 2238) struct trace_buffer *buffer = cpu_buffer->buffer;
4009cc31e7813e Steven Rostedt 2025-03-05 2239 struct ring_buffer_cpu_meta *meta = NULL;
044fa782ebb947 Steven Rostedt 2008-12-02 2240 struct buffer_page *bpage, *tmp;
927e56db625322 Steven Rostedt (VMware 2018-04-04 2241) bool user_thread = current->mm != NULL;
927e56db625322 Steven Rostedt (VMware 2018-04-04 @2242) gfp_t mflags;
9b94a8fba501f3 Steven Rostedt (Red Hat 2016-05-12 2243) long i;
3adc54fa82a68b Steven Rostedt 2009-03-30 2244
927e56db625322 Steven Rostedt (VMware 2018-04-04 2245) /*
927e56db625322 Steven Rostedt (VMware 2018-04-04 2246) * Check if the available memory is there first.
927e56db625322 Steven Rostedt (VMware 2018-04-04 2247) * Note, si_mem_available() only gives us a rough estimate of available
927e56db625322 Steven Rostedt (VMware 2018-04-04 2248) * memory. It may not be accurate. But we don't care, we just want
927e56db625322 Steven Rostedt (VMware 2018-04-04 2249) * to prevent doing any allocation when it is obvious that it is
927e56db625322 Steven Rostedt (VMware 2018-04-04 2250) * not going to succeed.
927e56db625322 Steven Rostedt (VMware 2018-04-04 2251) */
2a872fa4e9c8ad Steven Rostedt (VMware 2018-04-02 2252) i = si_mem_available();
2a872fa4e9c8ad Steven Rostedt (VMware 2018-04-02 2253) if (i < nr_pages)
2a872fa4e9c8ad Steven Rostedt (VMware 2018-04-02 2254) return -ENOMEM;
2a872fa4e9c8ad Steven Rostedt (VMware 2018-04-02 2255)
d7ec4bfed6c974 Vaibhav Nagarnaik 2011-06-07 2256 /*
848618857d2535 Joel Fernandes 2017-07-12 2257 * __GFP_RETRY_MAYFAIL flag makes sure that the allocation fails
848618857d2535 Joel Fernandes 2017-07-12 2258 * gracefully without invoking oom-killer and the system is not
848618857d2535 Joel Fernandes 2017-07-12 2259 * destabilized.
d7ec4bfed6c974 Vaibhav Nagarnaik 2011-06-07 2260 */
927e56db625322 Steven Rostedt (VMware 2018-04-04 2261) mflags = GFP_KERNEL | __GFP_RETRY_MAYFAIL;
927e56db625322 Steven Rostedt (VMware 2018-04-04 2262)
927e56db625322 Steven Rostedt (VMware 2018-04-04 2263) /*
927e56db625322 Steven Rostedt (VMware 2018-04-04 2264) * If a user thread allocates too much, and si_mem_available()
927e56db625322 Steven Rostedt (VMware 2018-04-04 2265) * reports there's enough memory, even though there is not.
927e56db625322 Steven Rostedt (VMware 2018-04-04 2266) * Make sure the OOM killer kills this thread. This can happen
927e56db625322 Steven Rostedt (VMware 2018-04-04 2267) * even with RETRY_MAYFAIL because another task may be doing
927e56db625322 Steven Rostedt (VMware 2018-04-04 2268) * an allocation after this task has taken all memory.
927e56db625322 Steven Rostedt (VMware 2018-04-04 2269) * This is the task the OOM killer needs to take out during this
927e56db625322 Steven Rostedt (VMware 2018-04-04 2270) * loop, even if it was triggered by an allocation somewhere else.
927e56db625322 Steven Rostedt (VMware 2018-04-04 2271) */
927e56db625322 Steven Rostedt (VMware 2018-04-04 2272) if (user_thread)
927e56db625322 Steven Rostedt (VMware 2018-04-04 2273) set_current_oom_origin();
c76883f18e59b7 Steven Rostedt (Google 2024-06-12 2274)
c76883f18e59b7 Steven Rostedt (Google 2024-06-12 2275) if (buffer->range_addr_start)
c76883f18e59b7 Steven Rostedt (Google 2024-06-12 2276) meta = rb_range_meta(buffer, nr_pages, cpu_buffer->cpu);
c76883f18e59b7 Steven Rostedt (Google 2024-06-12 2277)
927e56db625322 Steven Rostedt (VMware 2018-04-04 2278) for (i = 0; i < nr_pages; i++) {
927e56db625322 Steven Rostedt (VMware 2018-04-04 @2279) struct page *page;
927e56db625322 Steven Rostedt (VMware 2018-04-04 2280)
1e3d56c5556b8d Steven Rostedt 2025-11-24 2281 bpage = alloc_cpu_page(cpu_buffer->cpu);
044fa782ebb947 Steven Rostedt 2008-12-02 2282 if (!bpage)
e4c2ce82ca2710 Steven Rostedt 2008-10-01 2283 goto free_pages;
77ae365eca8950 Steven Rostedt 2009-03-27 2284
74e2afc6df5782 Qiujun Huang 2020-10-15 2285 rb_check_bpage(cpu_buffer, bpage);
74e2afc6df5782 Qiujun Huang 2020-10-15 2286
be68d63a139bd4 Steven Rostedt (Google 2024-06-12 2287) /*
be68d63a139bd4 Steven Rostedt (Google 2024-06-12 2288) * Append the pages as for mapped buffers we want to keep
be68d63a139bd4 Steven Rostedt (Google 2024-06-12 2289) * the order
be68d63a139bd4 Steven Rostedt (Google 2024-06-12 2290) */
be68d63a139bd4 Steven Rostedt (Google 2024-06-12 2291) list_add_tail(&bpage->list, pages);
e4c2ce82ca2710 Steven Rostedt 2008-10-01 2292
c76883f18e59b7 Steven Rostedt (Google 2024-06-12 2293) if (meta) {
be68d63a139bd4 Steven Rostedt (Google 2024-06-12 2294) /* A range was given. Use that for the buffer page */
b14d032973d4e6 Steven Rostedt (Google 2024-06-12 2295) bpage->page = rb_range_buffer(cpu_buffer, i + 1);
be68d63a139bd4 Steven Rostedt (Google 2024-06-12 2296) if (!bpage->page)
be68d63a139bd4 Steven Rostedt (Google 2024-06-12 2297) goto free_pages;
c76883f18e59b7 Steven Rostedt (Google 2024-06-12 2298) /* If this is valid from a previous boot */
c76883f18e59b7 Steven Rostedt (Google 2024-06-12 2299) if (meta->head_buffer)
c76883f18e59b7 Steven Rostedt (Google 2024-06-12 2300) rb_meta_buffer_update(cpu_buffer, bpage);
be68d63a139bd4 Steven Rostedt (Google 2024-06-12 2301) bpage->range = 1;
b14d032973d4e6 Steven Rostedt (Google 2024-06-12 2302) bpage->id = i + 1;
be68d63a139bd4 Steven Rostedt (Google 2024-06-12 2303) } else {
1e3d56c5556b8d Steven Rostedt 2025-11-24 2304 int order = cpu_buffer->buffer->subbuf_order;
1e3d56c5556b8d Steven Rostedt 2025-11-24 2305 bpage->page = alloc_cpu_data(cpu_buffer->cpu, order);
1e3d56c5556b8d Steven Rostedt 2025-11-24 2306 if (!bpage->page)
7a8e76a3829f10 Steven Rostedt 2008-09-29 2307 goto free_pages;
be68d63a139bd4 Steven Rostedt (Google 2024-06-12 2308) }
f9b94daa542a8d Tzvetomir Stoyanov (VMware 2023-12-19 2309) bpage->order = cpu_buffer->buffer->subbuf_order;
927e56db625322 Steven Rostedt (VMware 2018-04-04 2310)
927e56db625322 Steven Rostedt (VMware 2018-04-04 2311) if (user_thread && fatal_signal_pending(current))
927e56db625322 Steven Rostedt (VMware 2018-04-04 2312) goto free_pages;
7a8e76a3829f10 Steven Rostedt 2008-09-29 2313 }
927e56db625322 Steven Rostedt (VMware 2018-04-04 2314) if (user_thread)
927e56db625322 Steven Rostedt (VMware 2018-04-04 2315) clear_current_oom_origin();
7a8e76a3829f10 Steven Rostedt 2008-09-29 2316
438ced1720b584 Vaibhav Nagarnaik 2012-02-02 2317 return 0;
438ced1720b584 Vaibhav Nagarnaik 2012-02-02 2318
438ced1720b584 Vaibhav Nagarnaik 2012-02-02 2319 free_pages:
438ced1720b584 Vaibhav Nagarnaik 2012-02-02 2320 list_for_each_entry_safe(bpage, tmp, pages, list) {
438ced1720b584 Vaibhav Nagarnaik 2012-02-02 2321 list_del_init(&bpage->list);
438ced1720b584 Vaibhav Nagarnaik 2012-02-02 2322 free_buffer_page(bpage);
438ced1720b584 Vaibhav Nagarnaik 2012-02-02 2323 }
927e56db625322 Steven Rostedt (VMware 2018-04-04 2324) if (user_thread)
927e56db625322 Steven Rostedt (VMware 2018-04-04 2325) clear_current_oom_origin();
438ced1720b584 Vaibhav Nagarnaik 2012-02-02 2326
438ced1720b584 Vaibhav Nagarnaik 2012-02-02 2327 return -ENOMEM;
438ced1720b584 Vaibhav Nagarnaik 2012-02-02 2328 }
438ced1720b584 Vaibhav Nagarnaik 2012-02-02 2329
--
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