Re: [PATCH v4 5/5] Drivers: hv: Add support for movable memory regions

Re: [PATCH v4 5/5] Drivers: hv: Add support for movable memory regions

[kernel test robot]

Hi Stanislav,

kernel test robot noticed the following build warnings:

[auto build test WARNING on linus/master]
[also build test WARNING on next-20251010]
[cannot apply to v6.17]
[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/Stanislav-Kinsburskii/Drivers-hv-Refactor-and-rename-memory-region-handling-functions/20251010-111917
base:   linus/master
patch link:    https://lore.kernel.org/r/175976319844.16834.4747024333732752980.stgit%40skinsburskii-cloud-desktop.internal.cloudapp.net
patch subject: [PATCH v4 5/5] Drivers: hv: Add support for movable memory regions
config: x86_64-randconfig-006-20251010 (https://download.01.org/0day-ci/archive/20251011/202510110134.RmOV83Fz-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251011/202510110134.RmOV83Fz-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/202510110134.RmOV83Fz-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/hv/mshv_root_main.c:1410:11: warning: variable 'ret' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
    1410 |         else if (!mutex_trylock(&region->mutex))
         |                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/hv/mshv_root_main.c:1434:12: note: uninitialized use occurs here
    1434 |         WARN_ONCE(ret,
         |                   ^~~
   include/asm-generic/bug.h:152:18: note: expanded from macro 'WARN_ONCE'
     152 |         DO_ONCE_LITE_IF(condition, WARN, 1, format)
         |                         ^~~~~~~~~
   include/linux/once_lite.h:28:27: note: expanded from macro 'DO_ONCE_LITE_IF'
      28 |                 bool __ret_do_once = !!(condition);                     \
         |                                         ^~~~~~~~~
   drivers/hv/mshv_root_main.c:1410:7: note: remove the 'if' if its condition is always false
    1410 |         else if (!mutex_trylock(&region->mutex))
         |              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    1411 |                 goto out_fail;
         |                 ~~~~~~~~~~~~~
   drivers/hv/mshv_root_main.c:1406:9: note: initialize the variable 'ret' to silence this warning
    1406 |         int ret;
         |                ^
         |                 = 0
   1 warning generated.


vim +1410 drivers/hv/mshv_root_main.c

  1377	
  1378	/**
  1379	 * mshv_region_interval_invalidate - Invalidate a range of memory region
  1380	 * @mni: Pointer to the mmu_interval_notifier structure
  1381	 * @range: Pointer to the mmu_notifier_range structure
  1382	 * @cur_seq: Current sequence number for the interval notifier
  1383	 *
  1384	 * This function invalidates a memory region by remapping its pages with
  1385	 * no access permissions. It locks the region's mutex to ensure thread safety
  1386	 * and updates the sequence number for the interval notifier. If the range
  1387	 * is blockable, it uses a blocking lock; otherwise, it attempts a non-blocking
  1388	 * lock and returns false if unsuccessful.
  1389	 *
  1390	 * NOTE: Failure to invalidate a region is a serious error, as the pages will
  1391	 * be considered freed while they are still mapped by the hypervisor.
  1392	 * Any attempt to access such pages will likely crash the system.
  1393	 *
  1394	 * Return: true if the region was successfully invalidated, false otherwise.
  1395	 */
  1396	static bool
  1397	mshv_region_interval_invalidate(struct mmu_interval_notifier *mni,
  1398					const struct mmu_notifier_range *range,
  1399					unsigned long cur_seq)
  1400	{
  1401		struct mshv_mem_region *region = container_of(mni,
  1402							struct mshv_mem_region,
  1403							mni);
  1404		u64 page_offset, page_count;
  1405		unsigned long mstart, mend;
  1406		int ret;
  1407	
  1408		if (mmu_notifier_range_blockable(range))
  1409			mutex_lock(&region->mutex);
> 1410		else if (!mutex_trylock(&region->mutex))
  1411			goto out_fail;
  1412	
  1413		mmu_interval_set_seq(mni, cur_seq);
  1414	
  1415		mstart = max(range->start, region->start_uaddr);
  1416		mend = min(range->end, region->start_uaddr +
  1417			   (region->nr_pages << HV_HYP_PAGE_SHIFT));
  1418	
  1419		page_offset = HVPFN_DOWN(mstart - region->start_uaddr);
  1420		page_count = HVPFN_DOWN(mend - mstart);
  1421	
  1422		ret = mshv_region_remap_pages(region, HV_MAP_GPA_NO_ACCESS,
  1423					      page_offset, page_count);
  1424		if (ret)
  1425			goto out_fail;
  1426	
  1427		mshv_region_invalidate_pages(region, page_offset, page_count);
  1428	
  1429		mutex_unlock(&region->mutex);
  1430	
  1431		return true;
  1432	
  1433	out_fail:
  1434		WARN_ONCE(ret,
  1435			  "Failed to invalidate region %#llx-%#llx (range %#lx-%#lx, event: %u, pages %#llx-%#llx, mm: %#llx): %d\n",
  1436			  region->start_uaddr,
  1437			  region->start_uaddr + (region->nr_pages << HV_HYP_PAGE_SHIFT),
  1438			  range->start, range->end, range->event,
  1439			  page_offset, page_offset + page_count - 1, (u64)range->mm, ret);
  1440		return false;
  1441	}
  1442	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH v4 5/5] Drivers: hv: Add support for movable memory regions

[kernel test robot]

Hi Stanislav,

kernel test robot noticed the following build errors:

[auto build test ERROR on linus/master]
[also build test ERROR on next-20251010]
[cannot apply to v6.17]
[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/Stanislav-Kinsburskii/Drivers-hv-Refactor-and-rename-memory-region-handling-functions/20251010-111917
base:   linus/master
patch link:    https://lore.kernel.org/r/175976319844.16834.4747024333732752980.stgit%40skinsburskii-cloud-desktop.internal.cloudapp.net
patch subject: [PATCH v4 5/5] Drivers: hv: Add support for movable memory regions
config: x86_64-buildonly-randconfig-001-20251011 (https://download.01.org/0day-ci/archive/20251011/202510110819.km2ehSaB-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251011/202510110819.km2ehSaB-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/202510110819.km2ehSaB-lkp@intel.com/

All errors (new ones prefixed by >>):

>> mm/hmm.c:667:7: error: call to undeclared function 'mmu_interval_check_retry'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     667 |                 if (mmu_interval_check_retry(range->notifier,
         |                     ^
   1 error generated.


vim +/mmu_interval_check_retry +667 mm/hmm.c

7b86ac3371b70c3 Christoph Hellwig 2019-08-28  634  
9a4903e49e495bf Christoph Hellwig 2019-07-25  635  /**
9a4903e49e495bf Christoph Hellwig 2019-07-25  636   * hmm_range_fault - try to fault some address in a virtual address range
f970b977e068aa5 Jason Gunthorpe   2020-03-27  637   * @range:	argument structure
9a4903e49e495bf Christoph Hellwig 2019-07-25  638   *
be957c886d92aa9 Jason Gunthorpe   2020-05-01  639   * Returns 0 on success or one of the following error codes:
73231612dc7c907 Jérôme Glisse     2019-05-13  640   *
9a4903e49e495bf Christoph Hellwig 2019-07-25  641   * -EINVAL:	Invalid arguments or mm or virtual address is in an invalid vma
9a4903e49e495bf Christoph Hellwig 2019-07-25  642   *		(e.g., device file vma).
73231612dc7c907 Jérôme Glisse     2019-05-13  643   * -ENOMEM:	Out of memory.
9a4903e49e495bf Christoph Hellwig 2019-07-25  644   * -EPERM:	Invalid permission (e.g., asking for write and range is read
9a4903e49e495bf Christoph Hellwig 2019-07-25  645   *		only).
9a4903e49e495bf Christoph Hellwig 2019-07-25  646   * -EBUSY:	The range has been invalidated and the caller needs to wait for
9a4903e49e495bf Christoph Hellwig 2019-07-25  647   *		the invalidation to finish.
f970b977e068aa5 Jason Gunthorpe   2020-03-27  648   * -EFAULT:     A page was requested to be valid and could not be made valid
f970b977e068aa5 Jason Gunthorpe   2020-03-27  649   *              ie it has no backing VMA or it is illegal to access
74eee180b935fcb Jérôme Glisse     2017-09-08  650   *
f970b977e068aa5 Jason Gunthorpe   2020-03-27  651   * This is similar to get_user_pages(), except that it can read the page tables
f970b977e068aa5 Jason Gunthorpe   2020-03-27  652   * without mutating them (ie causing faults).
74eee180b935fcb Jérôme Glisse     2017-09-08  653   */
be957c886d92aa9 Jason Gunthorpe   2020-05-01  654  int hmm_range_fault(struct hmm_range *range)
74eee180b935fcb Jérôme Glisse     2017-09-08  655  {
d28c2c9a487708b Ralph Campbell    2019-11-04  656  	struct hmm_vma_walk hmm_vma_walk = {
d28c2c9a487708b Ralph Campbell    2019-11-04  657  		.range = range,
d28c2c9a487708b Ralph Campbell    2019-11-04  658  		.last = range->start,
d28c2c9a487708b Ralph Campbell    2019-11-04  659  	};
a22dd506400d0f4 Jason Gunthorpe   2019-11-12  660  	struct mm_struct *mm = range->notifier->mm;
74eee180b935fcb Jérôme Glisse     2017-09-08  661  	int ret;
74eee180b935fcb Jérôme Glisse     2017-09-08  662  
42fc541404f2497 Michel Lespinasse 2020-06-08  663  	mmap_assert_locked(mm);
74eee180b935fcb Jérôme Glisse     2017-09-08  664  
a3e0d41c2b1f86b Jérôme Glisse     2019-05-13  665  	do {
a3e0d41c2b1f86b Jérôme Glisse     2019-05-13  666  		/* If range is no longer valid force retry. */
a22dd506400d0f4 Jason Gunthorpe   2019-11-12 @667  		if (mmu_interval_check_retry(range->notifier,
a22dd506400d0f4 Jason Gunthorpe   2019-11-12  668  					     range->notifier_seq))
2bcbeaefde2f038 Christoph Hellwig 2019-07-24  669  			return -EBUSY;
d28c2c9a487708b Ralph Campbell    2019-11-04  670  		ret = walk_page_range(mm, hmm_vma_walk.last, range->end,
7b86ac3371b70c3 Christoph Hellwig 2019-08-28  671  				      &hmm_walk_ops, &hmm_vma_walk);
be957c886d92aa9 Jason Gunthorpe   2020-05-01  672  		/*
be957c886d92aa9 Jason Gunthorpe   2020-05-01  673  		 * When -EBUSY is returned the loop restarts with
be957c886d92aa9 Jason Gunthorpe   2020-05-01  674  		 * hmm_vma_walk.last set to an address that has not been stored
be957c886d92aa9 Jason Gunthorpe   2020-05-01  675  		 * in pfns. All entries < last in the pfn array are set to their
be957c886d92aa9 Jason Gunthorpe   2020-05-01  676  		 * output, and all >= are still at their input values.
be957c886d92aa9 Jason Gunthorpe   2020-05-01  677  		 */
d28c2c9a487708b Ralph Campbell    2019-11-04  678  	} while (ret == -EBUSY);
73231612dc7c907 Jérôme Glisse     2019-05-13  679  	return ret;
74eee180b935fcb Jérôme Glisse     2017-09-08  680  }
73231612dc7c907 Jérôme Glisse     2019-05-13  681  EXPORT_SYMBOL(hmm_range_fault);
8cad47130566123 Leon Romanovsky   2025-04-28  682  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki