* Re: [RFC] mm/page_isolation: Fix an infinite loop in isolate_single_pageblock()
[not found] <20220530115027.123341-1-anshuman.khandual@arm.com>
@ 2022-05-31 6:21 ` kernel test robot
0 siblings, 0 replies; only message in thread
From: kernel test robot @ 2022-05-31 6:21 UTC (permalink / raw)
To: Anshuman Khandual; +Cc: llvm, kbuild-all
Hi Anshuman,
[FYI, it's a private test report for your RFC patch.]
[auto build test WARNING on akpm-mm/mm-everything]
url: https://github.com/intel-lab-lkp/linux/commits/Anshuman-Khandual/mm-page_isolation-Fix-an-infinite-loop-in-isolate_single_pageblock/20220530-195220
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
config: x86_64-randconfig-a016 (https://download.01.org/0day-ci/archive/20220531/202205311448.NLkd29GM-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project c825abd6b0198fb088d9752f556a70705bc99dfd)
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/13632aee393de39b7f25b163df4d9fd6a29e4061
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Anshuman-Khandual/mm-page_isolation-Fix-an-infinite-loop-in-isolate_single_pageblock/20220530-195220
git checkout 13632aee393de39b7f25b163df4d9fd6a29e4061
# 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=x86_64 SHELL=/bin/bash
If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>
All warnings (new ones prefixed by >>):
>> mm/page_isolation.c:388:18: warning: unused variable 'nr_pages' [-Wunused-variable]
unsigned long nr_pages = compound_nr(page);
^
>> mm/page_isolation.c:390:18: warning: unused variable 'head_pfn' [-Wunused-variable]
unsigned long head_pfn = page_to_pfn(head);
^
2 warnings generated.
vim +/nr_pages +388 mm/page_isolation.c
a5d76b54a3f3a4 KAMEZAWA Hiroyuki 2007-10-16 281
b2c9e2fbba3253 Zi Yan 2022-05-12 282 /**
b2c9e2fbba3253 Zi Yan 2022-05-12 283 * isolate_single_pageblock() -- tries to isolate a pageblock that might be
b2c9e2fbba3253 Zi Yan 2022-05-12 284 * within a free or in-use page.
b2c9e2fbba3253 Zi Yan 2022-05-12 285 * @boundary_pfn: pageblock-aligned pfn that a page might cross
88ee134320b831 Zi Yan 2022-05-24 286 * @flags: isolation flags
b2c9e2fbba3253 Zi Yan 2022-05-12 287 * @gfp_flags: GFP flags used for migrating pages
b2c9e2fbba3253 Zi Yan 2022-05-12 288 * @isolate_before: isolate the pageblock before the boundary_pfn
b2c9e2fbba3253 Zi Yan 2022-05-12 289 *
b2c9e2fbba3253 Zi Yan 2022-05-12 290 * Free and in-use pages can be as big as MAX_ORDER-1 and contain more than one
b2c9e2fbba3253 Zi Yan 2022-05-12 291 * pageblock. When not all pageblocks within a page are isolated at the same
b2c9e2fbba3253 Zi Yan 2022-05-12 292 * time, free page accounting can go wrong. For example, in the case of
b2c9e2fbba3253 Zi Yan 2022-05-12 293 * MAX_ORDER-1 = pageblock_order + 1, a MAX_ORDER-1 page has two pagelbocks.
b2c9e2fbba3253 Zi Yan 2022-05-12 294 * [ MAX_ORDER-1 ]
b2c9e2fbba3253 Zi Yan 2022-05-12 295 * [ pageblock0 | pageblock1 ]
b2c9e2fbba3253 Zi Yan 2022-05-12 296 * When either pageblock is isolated, if it is a free page, the page is not
b2c9e2fbba3253 Zi Yan 2022-05-12 297 * split into separate migratetype lists, which is supposed to; if it is an
b2c9e2fbba3253 Zi Yan 2022-05-12 298 * in-use page and freed later, __free_one_page() does not split the free page
b2c9e2fbba3253 Zi Yan 2022-05-12 299 * either. The function handles this by splitting the free page or migrating
b2c9e2fbba3253 Zi Yan 2022-05-12 300 * the in-use page then splitting the free page.
b2c9e2fbba3253 Zi Yan 2022-05-12 301 */
88ee134320b831 Zi Yan 2022-05-24 302 static int isolate_single_pageblock(unsigned long boundary_pfn, int flags,
9b209e557d698f Zi Yan 2022-05-26 303 gfp_t gfp_flags, bool isolate_before, bool skip_isolation)
b2c9e2fbba3253 Zi Yan 2022-05-12 304 {
b2c9e2fbba3253 Zi Yan 2022-05-12 305 unsigned char saved_mt;
b2c9e2fbba3253 Zi Yan 2022-05-12 306 unsigned long start_pfn;
b2c9e2fbba3253 Zi Yan 2022-05-12 307 unsigned long isolate_pageblock;
b2c9e2fbba3253 Zi Yan 2022-05-12 308 unsigned long pfn;
b2c9e2fbba3253 Zi Yan 2022-05-12 309 struct zone *zone;
88ee134320b831 Zi Yan 2022-05-24 310 int ret;
b2c9e2fbba3253 Zi Yan 2022-05-12 311
b2c9e2fbba3253 Zi Yan 2022-05-12 312 VM_BUG_ON(!IS_ALIGNED(boundary_pfn, pageblock_nr_pages));
b2c9e2fbba3253 Zi Yan 2022-05-12 313
b2c9e2fbba3253 Zi Yan 2022-05-12 314 if (isolate_before)
b2c9e2fbba3253 Zi Yan 2022-05-12 315 isolate_pageblock = boundary_pfn - pageblock_nr_pages;
b2c9e2fbba3253 Zi Yan 2022-05-12 316 else
b2c9e2fbba3253 Zi Yan 2022-05-12 317 isolate_pageblock = boundary_pfn;
b2c9e2fbba3253 Zi Yan 2022-05-12 318
b2c9e2fbba3253 Zi Yan 2022-05-12 319 /*
b2c9e2fbba3253 Zi Yan 2022-05-12 320 * scan at the beginning of MAX_ORDER_NR_PAGES aligned range to avoid
b2c9e2fbba3253 Zi Yan 2022-05-12 321 * only isolating a subset of pageblocks from a bigger than pageblock
b2c9e2fbba3253 Zi Yan 2022-05-12 322 * free or in-use page. Also make sure all to-be-isolated pageblocks
b2c9e2fbba3253 Zi Yan 2022-05-12 323 * are within the same zone.
b2c9e2fbba3253 Zi Yan 2022-05-12 324 */
b2c9e2fbba3253 Zi Yan 2022-05-12 325 zone = page_zone(pfn_to_page(isolate_pageblock));
b2c9e2fbba3253 Zi Yan 2022-05-12 326 start_pfn = max(ALIGN_DOWN(isolate_pageblock, MAX_ORDER_NR_PAGES),
b2c9e2fbba3253 Zi Yan 2022-05-12 327 zone->zone_start_pfn);
b2c9e2fbba3253 Zi Yan 2022-05-12 328
b2c9e2fbba3253 Zi Yan 2022-05-12 329 saved_mt = get_pageblock_migratetype(pfn_to_page(isolate_pageblock));
9b209e557d698f Zi Yan 2022-05-26 330
9b209e557d698f Zi Yan 2022-05-26 331 if (skip_isolation)
9b209e557d698f Zi Yan 2022-05-26 332 VM_BUG_ON(!is_migrate_isolate(saved_mt));
9b209e557d698f Zi Yan 2022-05-26 333 else {
88ee134320b831 Zi Yan 2022-05-24 334 ret = set_migratetype_isolate(pfn_to_page(isolate_pageblock), saved_mt, flags,
88ee134320b831 Zi Yan 2022-05-24 335 isolate_pageblock, isolate_pageblock + pageblock_nr_pages);
88ee134320b831 Zi Yan 2022-05-24 336
88ee134320b831 Zi Yan 2022-05-24 337 if (ret)
88ee134320b831 Zi Yan 2022-05-24 338 return ret;
9b209e557d698f Zi Yan 2022-05-26 339 }
b2c9e2fbba3253 Zi Yan 2022-05-12 340
b2c9e2fbba3253 Zi Yan 2022-05-12 341 /*
b2c9e2fbba3253 Zi Yan 2022-05-12 342 * Bail out early when the to-be-isolated pageblock does not form
b2c9e2fbba3253 Zi Yan 2022-05-12 343 * a free or in-use page across boundary_pfn:
b2c9e2fbba3253 Zi Yan 2022-05-12 344 *
b2c9e2fbba3253 Zi Yan 2022-05-12 345 * 1. isolate before boundary_pfn: the page after is not online
b2c9e2fbba3253 Zi Yan 2022-05-12 346 * 2. isolate after boundary_pfn: the page before is not online
b2c9e2fbba3253 Zi Yan 2022-05-12 347 *
b2c9e2fbba3253 Zi Yan 2022-05-12 348 * This also ensures correctness. Without it, when isolate after
b2c9e2fbba3253 Zi Yan 2022-05-12 349 * boundary_pfn and [start_pfn, boundary_pfn) are not online,
b2c9e2fbba3253 Zi Yan 2022-05-12 350 * __first_valid_page() will return unexpected NULL in the for loop
b2c9e2fbba3253 Zi Yan 2022-05-12 351 * below.
b2c9e2fbba3253 Zi Yan 2022-05-12 352 */
b2c9e2fbba3253 Zi Yan 2022-05-12 353 if (isolate_before) {
b2c9e2fbba3253 Zi Yan 2022-05-12 354 if (!pfn_to_online_page(boundary_pfn))
b2c9e2fbba3253 Zi Yan 2022-05-12 355 return 0;
b2c9e2fbba3253 Zi Yan 2022-05-12 356 } else {
b2c9e2fbba3253 Zi Yan 2022-05-12 357 if (!pfn_to_online_page(boundary_pfn - 1))
b2c9e2fbba3253 Zi Yan 2022-05-12 358 return 0;
b2c9e2fbba3253 Zi Yan 2022-05-12 359 }
b2c9e2fbba3253 Zi Yan 2022-05-12 360
b2c9e2fbba3253 Zi Yan 2022-05-12 361 for (pfn = start_pfn; pfn < boundary_pfn;) {
b2c9e2fbba3253 Zi Yan 2022-05-12 362 struct page *page = __first_valid_page(pfn, boundary_pfn - pfn);
b2c9e2fbba3253 Zi Yan 2022-05-12 363
b2c9e2fbba3253 Zi Yan 2022-05-12 364 VM_BUG_ON(!page);
b2c9e2fbba3253 Zi Yan 2022-05-12 365 pfn = page_to_pfn(page);
b2c9e2fbba3253 Zi Yan 2022-05-12 366 /*
b2c9e2fbba3253 Zi Yan 2022-05-12 367 * start_pfn is MAX_ORDER_NR_PAGES aligned, if there is any
b2c9e2fbba3253 Zi Yan 2022-05-12 368 * free pages in [start_pfn, boundary_pfn), its head page will
b2c9e2fbba3253 Zi Yan 2022-05-12 369 * always be in the range.
b2c9e2fbba3253 Zi Yan 2022-05-12 370 */
b2c9e2fbba3253 Zi Yan 2022-05-12 371 if (PageBuddy(page)) {
b2c9e2fbba3253 Zi Yan 2022-05-12 372 int order = buddy_order(page);
b2c9e2fbba3253 Zi Yan 2022-05-12 373
86d28b0709279c Zi Yan 2022-05-26 374 if (pfn + (1UL << order) > boundary_pfn) {
86d28b0709279c Zi Yan 2022-05-26 375 /* free page changed before split, check it again */
86d28b0709279c Zi Yan 2022-05-26 376 if (split_free_page(page, order, boundary_pfn - pfn))
86d28b0709279c Zi Yan 2022-05-26 377 continue;
86d28b0709279c Zi Yan 2022-05-26 378 }
86d28b0709279c Zi Yan 2022-05-26 379
86d28b0709279c Zi Yan 2022-05-26 380 pfn += 1UL << order;
b2c9e2fbba3253 Zi Yan 2022-05-12 381 continue;
b2c9e2fbba3253 Zi Yan 2022-05-12 382 }
b2c9e2fbba3253 Zi Yan 2022-05-12 383 /*
b2c9e2fbba3253 Zi Yan 2022-05-12 384 * migrate compound pages then let the free page handling code
b2c9e2fbba3253 Zi Yan 2022-05-12 385 * above do the rest. If migration is not possible, just fail.
b2c9e2fbba3253 Zi Yan 2022-05-12 386 */
b2c9e2fbba3253 Zi Yan 2022-05-12 387 if (PageCompound(page)) {
b2c9e2fbba3253 Zi Yan 2022-05-12 @388 unsigned long nr_pages = compound_nr(page);
b2c9e2fbba3253 Zi Yan 2022-05-12 389 struct page *head = compound_head(page);
b2c9e2fbba3253 Zi Yan 2022-05-12 @390 unsigned long head_pfn = page_to_pfn(head);
b2c9e2fbba3253 Zi Yan 2022-05-12 391
--
0-DAY CI Kernel Test Service
https://01.org/lkp
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[not found] <20220530115027.123341-1-anshuman.khandual@arm.com>
2022-05-31 6:21 ` [RFC] mm/page_isolation: Fix an infinite loop in isolate_single_pageblock() kernel test robot
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