Re: [PATCH bpf-next v9 4/6] memcg: Use trylock to access memcg stock_lock.

[kernel test robot <lkp@intel.com>]

Hi Alexei,

kernel test robot noticed the following build warnings:

[auto build test WARNING on bpf-next/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Alexei-Starovoitov/locking-local_lock-Introduce-localtry_lock_t/20250222-104619
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/20250222024427.30294-5-alexei.starovoitov%40gmail.com
patch subject: [PATCH bpf-next v9 4/6] memcg: Use trylock to access memcg stock_lock.
config: x86_64-buildonly-randconfig-003-20250223 (https://download.01.org/0day-ci/archive/20250223/202502231159.uI2OsAAB-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250223/202502231159.uI2OsAAB-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@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202502231159.uI2OsAAB-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> mm/memcontrol.c:1778: warning: Function parameter or struct member 'gfp_mask' not described in 'consume_stock'


vim +1778 mm/memcontrol.c

cdec2e4265dfa09 KAMEZAWA Hiroyuki         2009-12-15  1760  
567511462387230 Sebastian Andrzej Siewior 2022-03-22  1761  static struct obj_cgroup *drain_obj_stock(struct memcg_stock_pcp *stock);
bf4f059954dcb22 Roman Gushchin            2020-08-06  1762  static bool obj_stock_flush_required(struct memcg_stock_pcp *stock,
bf4f059954dcb22 Roman Gushchin            2020-08-06  1763  				     struct mem_cgroup *root_memcg);
bf4f059954dcb22 Roman Gushchin            2020-08-06  1764  
a0956d54492eb72 Suleiman Souhlal          2012-12-18  1765  /**
a0956d54492eb72 Suleiman Souhlal          2012-12-18  1766   * consume_stock: Try to consume stocked charge on this cpu.
a0956d54492eb72 Suleiman Souhlal          2012-12-18  1767   * @memcg: memcg to consume from.
a0956d54492eb72 Suleiman Souhlal          2012-12-18  1768   * @nr_pages: how many pages to charge.
a0956d54492eb72 Suleiman Souhlal          2012-12-18  1769   *
a0956d54492eb72 Suleiman Souhlal          2012-12-18  1770   * The charges will only happen if @memcg matches the current cpu's memcg
a0956d54492eb72 Suleiman Souhlal          2012-12-18  1771   * stock, and at least @nr_pages are available in that stock.  Failure to
a0956d54492eb72 Suleiman Souhlal          2012-12-18  1772   * service an allocation will refill the stock.
a0956d54492eb72 Suleiman Souhlal          2012-12-18  1773   *
a0956d54492eb72 Suleiman Souhlal          2012-12-18  1774   * returns true if successful, false otherwise.
cdec2e4265dfa09 KAMEZAWA Hiroyuki         2009-12-15  1775   */
416c592ed9773a3 Alexei Starovoitov        2025-02-21  1776  static bool consume_stock(struct mem_cgroup *memcg, unsigned int nr_pages,
416c592ed9773a3 Alexei Starovoitov        2025-02-21  1777  			  gfp_t gfp_mask)
cdec2e4265dfa09 KAMEZAWA Hiroyuki         2009-12-15 @1778  {
cdec2e4265dfa09 KAMEZAWA Hiroyuki         2009-12-15  1779  	struct memcg_stock_pcp *stock;
1872b3bcd5874b5 Breno Leitao              2024-05-01  1780  	unsigned int stock_pages;
db2ba40c277dc54 Johannes Weiner           2016-09-19  1781  	unsigned long flags;
3e32cb2e0a12b69 Johannes Weiner           2014-12-10  1782  	bool ret = false;
cdec2e4265dfa09 KAMEZAWA Hiroyuki         2009-12-15  1783  
a983b5ebee57209 Johannes Weiner           2018-01-31  1784  	if (nr_pages > MEMCG_CHARGE_BATCH)
3e32cb2e0a12b69 Johannes Weiner           2014-12-10  1785  		return ret;
a0956d54492eb72 Suleiman Souhlal          2012-12-18  1786  
416c592ed9773a3 Alexei Starovoitov        2025-02-21  1787  	if (!localtry_trylock_irqsave(&memcg_stock.stock_lock, flags)) {
416c592ed9773a3 Alexei Starovoitov        2025-02-21  1788  		if (!gfpflags_allow_spinning(gfp_mask))
416c592ed9773a3 Alexei Starovoitov        2025-02-21  1789  			return ret;
416c592ed9773a3 Alexei Starovoitov        2025-02-21  1790  		localtry_lock_irqsave(&memcg_stock.stock_lock, flags);
416c592ed9773a3 Alexei Starovoitov        2025-02-21  1791  	}
db2ba40c277dc54 Johannes Weiner           2016-09-19  1792  
db2ba40c277dc54 Johannes Weiner           2016-09-19  1793  	stock = this_cpu_ptr(&memcg_stock);
1872b3bcd5874b5 Breno Leitao              2024-05-01  1794  	stock_pages = READ_ONCE(stock->nr_pages);
1872b3bcd5874b5 Breno Leitao              2024-05-01  1795  	if (memcg == READ_ONCE(stock->cached) && stock_pages >= nr_pages) {
1872b3bcd5874b5 Breno Leitao              2024-05-01  1796  		WRITE_ONCE(stock->nr_pages, stock_pages - nr_pages);
3e32cb2e0a12b69 Johannes Weiner           2014-12-10  1797  		ret = true;
3e32cb2e0a12b69 Johannes Weiner           2014-12-10  1798  	}
db2ba40c277dc54 Johannes Weiner           2016-09-19  1799  
416c592ed9773a3 Alexei Starovoitov        2025-02-21  1800  	localtry_unlock_irqrestore(&memcg_stock.stock_lock, flags);
db2ba40c277dc54 Johannes Weiner           2016-09-19  1801  
cdec2e4265dfa09 KAMEZAWA Hiroyuki         2009-12-15  1802  	return ret;
cdec2e4265dfa09 KAMEZAWA Hiroyuki         2009-12-15  1803  }
cdec2e4265dfa09 KAMEZAWA Hiroyuki         2009-12-15  1804  

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