Re: [PATCH 3/3] virtio_balloon: Introduce memory recover

[kernel test robot]

Hi zhenwei,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on akpm-mm/mm-everything]
[also build test WARNING on next-20220519]
[cannot apply to linux/master linus/master v5.18-rc7]
[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/intel-lab-lkp/linux/commits/zhenwei-pi/recover-hardware-corrupted-page-by-virtio-balloon/20220520-151328
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
config: hexagon-randconfig-r041-20220519 (https://download.01.org/0day-ci/archive/20220520/202205202014.mgqgBrKd-lkp@xxxxxxxxx/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project e00cbbec06c08dc616a0d52a20f678b8fbd4e304)
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
        # https://github.com/intel-lab-lkp/linux/commit/a42127073dd4adb6354649c8235c5cde033d01f2
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review zhenwei-pi/recover-hardware-corrupted-page-by-virtio-balloon/20220520-151328
        git checkout a42127073dd4adb6354649c8235c5cde033d01f2
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash drivers/virtio/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@xxxxxxxxx>

All warnings (new ones prefixed by >>):

>> drivers/virtio/virtio_balloon.c:654:2: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
           default:
           ^
   drivers/virtio/virtio_balloon.c:654:2: note: insert 'break;' to avoid fall-through
           default:
           ^
           break; 
   1 warning generated.


vim +654 drivers/virtio/virtio_balloon.c

   593	
   594	static void recover_vq_handle_response(struct virtio_balloon *vb, unsigned int len)
   595	{
   596		struct __virtio_balloon_recover *in_vbr;
   597		struct virtio_balloon_recover *vbr;
   598		struct page *page;
   599		unsigned int pfns;
   600		u32 pfn0, pfn1;
   601		__u8 status;
   602	
   603		/* the response is not expected */
   604		if (unlikely(len != sizeof(struct __virtio_balloon_recover)))
   605			return;
   606	
   607		in_vbr = &vb->in_vbr;
   608		vbr = &in_vbr->vbr;
   609		if (unlikely(vbr->cmd != VIRTIO_BALLOON_R_CMD_RESPONSE))
   610			return;
   611	
   612		/* to make sure the contiguous balloon PFNs */
   613		for (pfns = 1; pfns < VIRTIO_BALLOON_PAGES_PER_PAGE; pfns++) {
   614			pfn0 = virtio32_to_cpu(vb->vdev, in_vbr->pfns[pfns - 1]);
   615			pfn1 = virtio32_to_cpu(vb->vdev, in_vbr->pfns[pfns]);
   616			if (pfn1 - pfn0 != 1)
   617				return;
   618		}
   619	
   620		pfn0 = virtio32_to_cpu(vb->vdev, in_vbr->pfns[0]);
   621		if (!pfn_valid(pfn0))
   622			return;
   623	
   624		pfn1 = -1;
   625		spin_lock(&vb->recover_page_list_lock);
   626		list_for_each_entry(page, &vb->corrupted_page_list, lru) {
   627			pfn1 = page_to_pfn(page);
   628			if (pfn1 == pfn0)
   629				break;
   630		}
   631		spin_unlock(&vb->recover_page_list_lock);
   632	
   633		status = vbr->status;
   634		switch (status) {
   635		case VIRTIO_BALLOON_R_STATUS_RECOVERED:
   636			if (pfn1 == pfn0) {
   637				spin_lock(&vb->recover_page_list_lock);
   638				list_del(&page->lru);
   639				balloon_page_push(&vb->recovered_page_list, page);
   640				spin_unlock(&vb->recover_page_list_lock);
   641				queue_work(system_freezable_wq, &vb->unpoison_memory_work);
   642				dev_info_ratelimited(&vb->vdev->dev, "recovered pfn 0x%x", pfn0);
   643			}
   644			break;
   645		case VIRTIO_BALLOON_R_STATUS_FAILED:
   646			/* the hypervisor can't fix this corrupted page, balloon puts page */
   647			if (pfn1 == pfn0) {
   648				spin_lock(&vb->recover_page_list_lock);
   649				list_del(&page->lru);
   650				spin_unlock(&vb->recover_page_list_lock);
   651				put_page(page);
   652				dev_info_ratelimited(&vb->vdev->dev, "failed to recover pfn 0x%x", pfn0);
   653			}
 > 654		default:
   655			break;
   656		};
   657	
   658		/* continue to get response from host side if the response gets handled successfully */
   659		recover_vq_get_response(vb);
   660	}
   661	

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