linux-kernel - Re: [PATCH 6/6] mm: Add memalloc

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Date:   Fri, 26 Jun 2020 07:51:38 +0800
From:   kernel test robot <lkp@...el.com>
To:     "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Cc:     kbuild-all@...ts.01.org, clang-built-linux@...glegroups.com,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        linux-xfs@...r.kernel.org, dm-devel@...hat.com,
        Mikulas Patocka <mpatocka@...hat.com>,
        Jens Axboe <axboe@...nel.dk>, NeilBrown <neilb@...e.de>
Subject: Re: [PATCH 6/6] mm: Add memalloc_nowait

Hi "Matthew,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on tip/sched/core]
[also build test ERROR on dm/for-next linus/master v5.8-rc2]
[cannot apply to xfs-linux/for-next next-20200625]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use  as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Matthew-Wilcox-Oracle/Overhaul-memalloc_no/20200625-193357
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 87e867b4269f29dac8190bca13912d08163a277f
config: x86_64-allyesconfig (attached as .config)
compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project 8911a35180c6777188fefe0954a2451a2b91deaf)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@...el.com>

All errors (new ones prefixed by >>):

>> drivers/md/dm-bufio.c:860:27: error: implicit declaration of function 'memalloc_nowait_save' [-Werror,-Wimplicit-function-declaration]
                           unsigned nowait_flag = memalloc_nowait_save();
                                                  ^
   drivers/md/dm-bufio.c:860:27: note: did you mean 'memalloc_noio_save'?
   include/linux/sched/mm.h:227:28: note: 'memalloc_noio_save' declared here
   static inline unsigned int memalloc_noio_save(void)
                              ^
>> drivers/md/dm-bufio.c:862:4: error: implicit declaration of function 'memalloc_nowait_restore' [-Werror,-Wimplicit-function-declaration]
                           memalloc_nowait_restore(nowait_flag);
                           ^
   drivers/md/dm-bufio.c:862:4: note: did you mean 'memalloc_noio_restore'?
   include/linux/sched/mm.h:242:20: note: 'memalloc_noio_restore' declared here
   static inline void memalloc_noio_restore(unsigned int flags)
                      ^
   2 errors generated.

vim +/memalloc_nowait_save +860 drivers/md/dm-bufio.c

   836	
   837	/*
   838	 * Allocate a new buffer. If the allocation is not possible, wait until
   839	 * some other thread frees a buffer.
   840	 *
   841	 * May drop the lock and regain it.
   842	 */
   843	static struct dm_buffer *__alloc_buffer_wait_no_callback(struct dm_bufio_client *c, enum new_flag nf)
   844	{
   845		struct dm_buffer *b;
   846		bool tried_noio_alloc = false;
   847	
   848		/*
   849		 * dm-bufio is resistant to allocation failures (it just keeps
   850		 * one buffer reserved in cases all the allocations fail).
   851		 * So set flags to not try too hard:
   852		 *	__GFP_NOMEMALLOC: don't use emergency reserves
   853		 *	__GFP_NOWARN: don't print a warning in case of failure
   854		 *
   855		 * For debugging, if we set the cache size to 1, no new buffers will
   856		 * be allocated.
   857		 */
   858		while (1) {
   859			if (dm_bufio_cache_size_latch != 1) {
 > 860				unsigned nowait_flag = memalloc_nowait_save();
   861				b = alloc_buffer(c, GFP_KERNEL | __GFP_NOMEMALLOC | __GFP_NOWARN);
 > 862				memalloc_nowait_restore(nowait_flag);
   863				if (b)
   864					return b;
   865			}
   866	
   867			if (nf == NF_PREFETCH)
   868				return NULL;
   869	
   870			if (dm_bufio_cache_size_latch != 1 && !tried_noio_alloc) {
   871				unsigned noio_flag;
   872	
   873				dm_bufio_unlock(c);
   874				noio_flag = memalloc_noio_save();
   875				b = alloc_buffer(c, GFP_KERNEL | __GFP_NOMEMALLOC | __GFP_NOWARN);
   876				memalloc_noio_restore(noio_flag);
   877				dm_bufio_lock(c);
   878				if (b)
   879					return b;
   880				tried_noio_alloc = true;
   881			}
   882	
   883			if (!list_empty(&c->reserved_buffers)) {
   884				b = list_entry(c->reserved_buffers.next,
   885					       struct dm_buffer, lru_list);
   886				list_del(&b->lru_list);
   887				c->need_reserved_buffers++;
   888	
   889				return b;
   890			}
   891	
   892			b = __get_unclaimed_buffer(c);
   893			if (b)
   894				return b;
   895	
   896			__wait_for_free_buffer(c);
   897		}
   898	}
   899	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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