Re: [PATCH v2] x86/sgx: Fix RCU Tasks stalls in EPC sanitization loop

Hi Jun,

kernel test robot noticed the following build errors:

[auto build test ERROR on linus/master]
[also build test ERROR on tip/x86/sgx v7.2 next-20260817]
[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/Jun-Miao/x86-sgx-Fix-RCU-Tasks-stalls-in-EPC-sanitization-loop/20260815-121253
base:   linus/master
patch link:    https://lore.kernel.org/r/20260623030329.2786571-1-jun.miao%40intel.com
patch subject: [PATCH v2] x86/sgx: Fix RCU Tasks stalls in EPC sanitization loop
config: x86_64-rhel-9.4-bpf (https://download.01.org/0day-ci/archive/20260818/[email protected]/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260818/[email protected]/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 <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/

All errors (new ones prefixed by >>):

   arch/x86/kernel/cpu/sgx/main.c: In function '__sgx_sanitize_pages':
>> arch/x86/kernel/cpu/sgx/main.c:109:17: error: implicit declaration of function 'cond_resched_rcu_qs'; did you mean 'cond_resched_lock'? [-Wimplicit-function-declaration]
     109 |                 cond_resched_rcu_qs();
         |                 ^~~~~~~~~~~~~~~~~~~
         |                 cond_resched_lock


vim +109 arch/x86/kernel/cpu/sgx/main.c

    54	
    55	/*
    56	 * Reset post-kexec EPC pages to the uninitialized state. The pages are removed
    57	 * from the input list, and made available for the page allocator. SECS pages
    58	 * prepending their children in the input list are left intact.
    59	 *
    60	 * Return 0 when sanitization was successful or kthread was stopped, and the
    61	 * number of unsanitized pages otherwise.
    62	 */
    63	static unsigned long __sgx_sanitize_pages(struct list_head *dirty_page_list)
    64	{
    65		unsigned long left_dirty = 0;
    66		struct sgx_epc_page *page;
    67		LIST_HEAD(dirty);
    68		int ret;
    69	
    70		/* dirty_page_list is thread-local, no need for a lock: */
    71		while (!list_empty(dirty_page_list)) {
    72			if (kthread_should_stop())
    73				return 0;
    74	
    75			page = list_first_entry(dirty_page_list, struct sgx_epc_page, list);
    76	
    77			/*
    78			 * Checking page->poison without holding the node->lock
    79			 * is racy, but losing the race (i.e. poison is set just
    80			 * after the check) just means __eremove() will be uselessly
    81			 * called for a page that sgx_free_epc_page() will put onto
    82			 * the node->sgx_poison_page_list later.
    83			 */
    84			if (page->poison) {
    85				struct sgx_epc_section *section = &sgx_epc_sections[page->section];
    86				struct sgx_numa_node *node = section->node;
    87	
    88				spin_lock(&node->lock);
    89				list_move(&page->list, &node->sgx_poison_page_list);
    90				spin_unlock(&node->lock);
    91	
    92				continue;
    93			}
    94	
    95			ret = __eremove(sgx_get_epc_virt_addr(page));
    96			if (!ret) {
    97				/*
    98				 * page is now sanitized.  Make it available via the SGX
    99				 * page allocator:
   100				 */
   101				list_del(&page->list);
   102				sgx_free_epc_page(page);
   103			} else {
   104				/* The page is not yet clean - move to the dirty list. */
   105				list_move_tail(&page->list, &dirty);
   106				left_dirty++;
   107			}
   108	
 > 109			cond_resched_rcu_qs();
   110		}
   111	
   112		list_splice(&dirty, dirty_page_list);
   113		return left_dirty;
   114	}
   115	

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