Hi Jan, I love your patch! Perhaps something to improve: [auto build test WARNING on ext4/dev] [also build test WARNING on fuse/for-next linus/master v5.12-rc8] [cannot apply to hnaz-linux-mm/master next-20210423] [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/Jan-Kara/fs-Hole-punch-vs-page-cache-filling-races/20210424-013114 base: https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git dev config: s390-randconfig-s031-20210424 (attached as .config) compiler: s390-linux-gcc (GCC) 9.3.0 reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # apt-get install sparse # sparse version: v0.6.3-341-g8af24329-dirty # https://github.com/0day-ci/linux/commit/800cf89f11d437415eead2da969c3b07908fd406 git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Jan-Kara/fs-Hole-punch-vs-page-cache-filling-races/20210424-013114 git checkout 800cf89f11d437415eead2da969c3b07908fd406 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' W=1 ARCH=s390 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp@xxxxxxxxx> All warnings (new ones prefixed by >>): mm/shmem.c: In function 'shmem_writepage': >> mm/shmem.c:1326:10: warning: variable 'index' set but not used [-Wunused-but-set-variable] 1326 | pgoff_t index; | ^~~~~ vim +/index +1326 mm/shmem.c ^1da177e4c3f41 Linus Torvalds 2005-04-16 1316 ^1da177e4c3f41 Linus Torvalds 2005-04-16 1317 /* ^1da177e4c3f41 Linus Torvalds 2005-04-16 1318 * Move the page from the page cache to the swap cache. ^1da177e4c3f41 Linus Torvalds 2005-04-16 1319 */ ^1da177e4c3f41 Linus Torvalds 2005-04-16 1320 static int shmem_writepage(struct page *page, struct writeback_control *wbc) ^1da177e4c3f41 Linus Torvalds 2005-04-16 1321 { ^1da177e4c3f41 Linus Torvalds 2005-04-16 1322 struct shmem_inode_info *info; ^1da177e4c3f41 Linus Torvalds 2005-04-16 1323 struct address_space *mapping; ^1da177e4c3f41 Linus Torvalds 2005-04-16 1324 struct inode *inode; 6922c0c7abd387 Hugh Dickins 2011-08-03 1325 swp_entry_t swap; 6922c0c7abd387 Hugh Dickins 2011-08-03 @1326 pgoff_t index; ^1da177e4c3f41 Linus Torvalds 2005-04-16 1327 800d8c63b2e989 Kirill A. Shutemov 2016-07-26 1328 VM_BUG_ON_PAGE(PageCompound(page), page); ^1da177e4c3f41 Linus Torvalds 2005-04-16 1329 BUG_ON(!PageLocked(page)); ^1da177e4c3f41 Linus Torvalds 2005-04-16 1330 mapping = page->mapping; ^1da177e4c3f41 Linus Torvalds 2005-04-16 1331 index = page->index; ^1da177e4c3f41 Linus Torvalds 2005-04-16 1332 inode = mapping->host; ^1da177e4c3f41 Linus Torvalds 2005-04-16 1333 info = SHMEM_I(inode); ^1da177e4c3f41 Linus Torvalds 2005-04-16 1334 if (info->flags & VM_LOCKED) ^1da177e4c3f41 Linus Torvalds 2005-04-16 1335 goto redirty; d9fe526a83b84e Hugh Dickins 2008-02-04 1336 if (!total_swap_pages) ^1da177e4c3f41 Linus Torvalds 2005-04-16 1337 goto redirty; ^1da177e4c3f41 Linus Torvalds 2005-04-16 1338 d9fe526a83b84e Hugh Dickins 2008-02-04 1339 /* 97b713ba3ebaa6 Christoph Hellwig 2015-01-14 1340 * Our capabilities prevent regular writeback or sync from ever calling 97b713ba3ebaa6 Christoph Hellwig 2015-01-14 1341 * shmem_writepage; but a stacking filesystem might use ->writepage of 97b713ba3ebaa6 Christoph Hellwig 2015-01-14 1342 * its underlying filesystem, in which case tmpfs should write out to 97b713ba3ebaa6 Christoph Hellwig 2015-01-14 1343 * swap only in response to memory pressure, and not for the writeback 97b713ba3ebaa6 Christoph Hellwig 2015-01-14 1344 * threads or sync. d9fe526a83b84e Hugh Dickins 2008-02-04 1345 */ 48f170fb7d7db8 Hugh Dickins 2011-07-25 1346 if (!wbc->for_reclaim) { 48f170fb7d7db8 Hugh Dickins 2011-07-25 1347 WARN_ON_ONCE(1); /* Still happens? Tell us about it! */ 48f170fb7d7db8 Hugh Dickins 2011-07-25 1348 goto redirty; 48f170fb7d7db8 Hugh Dickins 2011-07-25 1349 } 1635f6a74152f1 Hugh Dickins 2012-05-29 1350 1635f6a74152f1 Hugh Dickins 2012-05-29 1351 /* 1635f6a74152f1 Hugh Dickins 2012-05-29 1352 * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC 1635f6a74152f1 Hugh Dickins 2012-05-29 1353 * value into swapfile.c, the only way we can correctly account for a 1635f6a74152f1 Hugh Dickins 2012-05-29 1354 * fallocated page arriving here is now to initialize it and write it. 800cf89f11d437 Jan Kara 2021-04-23 1355 * Since a page added by currently running fallocate call cannot be 800cf89f11d437 Jan Kara 2021-04-23 1356 * dirtied and thus arrive here we know the fallocate has already 800cf89f11d437 Jan Kara 2021-04-23 1357 * completed and we are fine writing it out. 1635f6a74152f1 Hugh Dickins 2012-05-29 1358 */ 1635f6a74152f1 Hugh Dickins 2012-05-29 1359 if (!PageUptodate(page)) { 1635f6a74152f1 Hugh Dickins 2012-05-29 1360 clear_highpage(page); 1635f6a74152f1 Hugh Dickins 2012-05-29 1361 flush_dcache_page(page); 1635f6a74152f1 Hugh Dickins 2012-05-29 1362 SetPageUptodate(page); 1635f6a74152f1 Hugh Dickins 2012-05-29 1363 } 1635f6a74152f1 Hugh Dickins 2012-05-29 1364 38d8b4e6bdc872 Huang Ying 2017-07-06 1365 swap = get_swap_page(page); 48f170fb7d7db8 Hugh Dickins 2011-07-25 1366 if (!swap.val) 48f170fb7d7db8 Hugh Dickins 2011-07-25 1367 goto redirty; d9fe526a83b84e Hugh Dickins 2008-02-04 1368 b1dea800ac3959 Hugh Dickins 2011-05-11 1369 /* b1dea800ac3959 Hugh Dickins 2011-05-11 1370 * Add inode to shmem_unuse()'s list of swapped-out inodes, 6922c0c7abd387 Hugh Dickins 2011-08-03 1371 * if it's not already there. Do it now before the page is 6922c0c7abd387 Hugh Dickins 2011-08-03 1372 * moved to swap cache, when its pagelock no longer protects b1dea800ac3959 Hugh Dickins 2011-05-11 1373 * the inode from eviction. But don't unlock the mutex until 6922c0c7abd387 Hugh Dickins 2011-08-03 1374 * we've incremented swapped, because shmem_unuse_inode() will 6922c0c7abd387 Hugh Dickins 2011-08-03 1375 * prune a !swapped inode from the swaplist under this mutex. b1dea800ac3959 Hugh Dickins 2011-05-11 1376 */ b1dea800ac3959 Hugh Dickins 2011-05-11 1377 mutex_lock(&shmem_swaplist_mutex); 05bf86b4ccfd0f Hugh Dickins 2011-05-14 1378 if (list_empty(&info->swaplist)) b56a2d8af9147a Vineeth Remanan Pillai 2019-03-05 1379 list_add(&info->swaplist, &shmem_swaplist); b1dea800ac3959 Hugh Dickins 2011-05-11 1380 4afab1cd256e42 Yang Shi 2019-11-30 1381 if (add_to_swap_cache(page, swap, 3852f6768ede54 Joonsoo Kim 2020-08-11 1382 __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN, 3852f6768ede54 Joonsoo Kim 2020-08-11 1383 NULL) == 0) { 4595ef88d13613 Kirill A. Shutemov 2016-07-26 1384 spin_lock_irq(&info->lock); 6922c0c7abd387 Hugh Dickins 2011-08-03 1385 shmem_recalc_inode(inode); 267a4c76bbdb95 Hugh Dickins 2015-12-11 1386 info->swapped++; 4595ef88d13613 Kirill A. Shutemov 2016-07-26 1387 spin_unlock_irq(&info->lock); 6922c0c7abd387 Hugh Dickins 2011-08-03 1388 267a4c76bbdb95 Hugh Dickins 2015-12-11 1389 swap_shmem_alloc(swap); 267a4c76bbdb95 Hugh Dickins 2015-12-11 1390 shmem_delete_from_page_cache(page, swp_to_radix_entry(swap)); 267a4c76bbdb95 Hugh Dickins 2015-12-11 1391 6922c0c7abd387 Hugh Dickins 2011-08-03 1392 mutex_unlock(&shmem_swaplist_mutex); d9fe526a83b84e Hugh Dickins 2008-02-04 1393 BUG_ON(page_mapped(page)); 9fab5619bdd7f8 Hugh Dickins 2009-03-31 1394 swap_writepage(page, wbc); ^1da177e4c3f41 Linus Torvalds 2005-04-16 1395 return 0; ^1da177e4c3f41 Linus Torvalds 2005-04-16 1396 } ^1da177e4c3f41 Linus Torvalds 2005-04-16 1397 6922c0c7abd387 Hugh Dickins 2011-08-03 1398 mutex_unlock(&shmem_swaplist_mutex); 75f6d6d29a40b5 Minchan Kim 2017-07-06 1399 put_swap_page(page, swap); ^1da177e4c3f41 Linus Torvalds 2005-04-16 1400 redirty: ^1da177e4c3f41 Linus Torvalds 2005-04-16 1401 set_page_dirty(page); d9fe526a83b84e Hugh Dickins 2008-02-04 1402 if (wbc->for_reclaim) d9fe526a83b84e Hugh Dickins 2008-02-04 1403 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ d9fe526a83b84e Hugh Dickins 2008-02-04 1404 unlock_page(page); d9fe526a83b84e Hugh Dickins 2008-02-04 1405 return 0; ^1da177e4c3f41 Linus Torvalds 2005-04-16 1406 } ^1da177e4c3f41 Linus Torvalds 2005-04-16 1407 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx
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