Re: [PATCH RFC 05/15] fsnotify: Support event submission through ring buffer

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

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Hi Gabriel,

[FYI, it's a private test report for your RFC patch.]
[auto build test WARNING on pcmoore-audit/next]
[also build test WARNING on ext4/dev linus/master v5.12]
[cannot apply to ext3/fsnotify next-20210426]
[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]

url:    https://github.com/0day-ci/linux/commits/Gabriel-Krisman-Bertazi/File-system-wide-monitoring/20210427-024627
base:   https://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit.git next
config: arm-randconfig-r022-20210426 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project d941863de2becb3d8d2e00676fc7125974934c7f)
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 arm cross compiling tool for clang build
        # apt-get install binutils-arm-linux-gnueabi
        # https://github.com/0day-ci/linux/commit/0b550d36bb2ec4613ad64b68b18898a72fd5af50
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Gabriel-Krisman-Bertazi/File-system-wide-monitoring/20210427-024627
        git checkout 0b550d36bb2ec4613ad64b68b18898a72fd5af50
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=arm 

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

All warnings (new ones prefixed by >>):

>> fs/notify/ring.c:82:15: warning: format specifies type 'unsigned long' but the argument has type 'size_t' (aka 'unsigned int') [-Wformat]
                    ring_size, size);
                               ^~~~
   include/linux/printk.h:430:38: note: expanded from macro 'pr_debug'
           no_printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
                                       ~~~     ^~~~~~~~~~~
   include/linux/printk.h:140:17: note: expanded from macro 'no_printk'
                   printk(fmt, ##__VA_ARGS__);             \
                          ~~~    ^~~~~~~~~~~
   1 warning generated.


vim +82 fs/notify/ring.c

    67	
    68	struct fsnotify_event *fsnotify_ring_alloc_event_slot(struct fsnotify_group *group,
    69							      size_t size)
    70		__acquires(&group->notification_lock)
    71	{
    72		struct fsnotify_event *fsn;
    73		u64 head, tail;
    74		u64 ring_size = group->ring_buffer.nr_pages << PAGE_SHIFT;
    75		u64 new_head;
    76		void *kaddr;
    77	
    78		if (WARN_ON(!(group->flags & FSN_SUBMISSION_RING_BUFFER) || size > PAGE_SIZE))
    79			return ERR_PTR(-EINVAL);
    80	
    81		pr_debug("%s: start group=%p ring_size=%llu, requested=%lu\n", __func__, group,
  > 82			 ring_size, size);
    83	
    84		spin_lock(&group->notification_lock);
    85	again:
    86		head = group->ring_buffer.head;
    87		tail = group->ring_buffer.tail;
    88		new_head = NEXT_SLOT(head, size, ring_size);
    89	
    90		/* head would catch up to tail, corrupting an entry. */
    91		if ((head < tail && new_head > tail) || (head > new_head && new_head > tail)) {
    92			fsn = ERR_PTR(-ENOMEM);
    93			goto err;
    94		}
    95	
    96		/*
    97		 * Not event a skip message fits in the page. We can detect the
    98		 * lack of space. Move on to the next page.
    99		 */
   100		if ((PAGE_SIZE - (head & (PAGE_SIZE-1))) < sizeof(struct fsnotify_event)) {
   101			/* Start again on next page */
   102			group->ring_buffer.head = NEXT_PAGE(head, ring_size);
   103			goto again;
   104		}
   105	
   106		kaddr = kmap_atomic(group->ring_buffer.pages[head / PAGE_SIZE]);
   107		if (!kaddr) {
   108			fsn = ERR_PTR(-EFAULT);
   109			goto err;
   110		}
   111	
   112		fsn = (struct fsnotify_event *) (kaddr + (head & (PAGE_SIZE-1)));
   113	
   114		if ((head >> PAGE_SHIFT) != (new_head >> PAGE_SHIFT)) {
   115			/*
   116			 * No room in the current page.  Add a fake entry
   117			 * consuming the end the page to avoid splitting event
   118			 * structure.
   119			 */
   120			fsn->slot_len = INVALID_RING_SLOT;
   121			kunmap_atomic(kaddr);
   122			/* Start again on the next page */
   123			group->ring_buffer.head = NEXT_PAGE(head, ring_size);
   124	
   125			goto again;
   126		}
   127		fsn->slot_len = size;
   128	
   129		return fsn;
   130	
   131	err:
   132		spin_unlock(&group->notification_lock);
   133		return fsn;
   134	}
   135	

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

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