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Message-ID: <202111160409.g1ZDJ3SZ-lkp@intel.com>
Date: Tue, 16 Nov 2021 04:40:48 +0800
From: kernel test robot <lkp@...el.com>
To: Alistair Popple <apopple@...dia.com>, akpm@...ux-foundation.org
Cc: llvm@...ts.linux.dev, kbuild-all@...ts.01.org, willy@...radead.org,
dhowells@...hat.com, hughd@...gle.com,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
jglisse@...hat.com, jgg@...dia.com, rcampbell@...dia.com,
jhubbard@...dia.com
Subject: Re: [PATCH v3] mm/migrate.c: Rework migration_entry_wait() to not
take a pageref
Hi Alistair,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on linux/master]
[also build test WARNING on linus/master v5.16-rc1 next-20211115]
[cannot apply to hnaz-mm/master]
[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/Alistair-Popple/mm-migrate-c-Rework-migration_entry_wait-to-not-take-a-pageref/20211115-185444
base: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git debe436e77c72fcee804fb867f275e6d31aa999c
config: i386-randconfig-r015-20211115 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project fbe72e41b99dc7994daac300d208a955be3e4a0a)
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/0day-ci/linux/commit/91a437ddc7606450e331059d80babe2d4c1163e0
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Alistair-Popple/mm-migrate-c-Rework-migration_entry_wait-to-not-take-a-pageref/20211115-185444
git checkout 91a437ddc7606450e331059d80babe2d4c1163e0
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=i386
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@...el.com>
All warnings (new ones prefixed by >>):
>> mm/filemap.c:1447:6: warning: no previous prototype for function 'migration_entry_wait_on_locked' [-Wmissing-prototypes]
void migration_entry_wait_on_locked(struct folio *folio, pte_t *ptep,
^
mm/filemap.c:1447:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
void migration_entry_wait_on_locked(struct folio *folio, pte_t *ptep,
^
static
1 warning generated.
vim +/migration_entry_wait_on_locked +1447 mm/filemap.c
1428
1429 #ifdef CONFIG_MIGRATION
1430 /**
1431 * migration_entry_wait_on_locked - Wait for a migration entry to be removed
1432 * @page: page referenced by the migration entry.
1433 * @ptep: mapped pte pointer. This function will return with the ptep unmapped.
1434 * @ptl: already locked ptl. This function will drop the lock.
1435 *
1436 * Wait for a migration entry referencing the given page to be removed. This is
1437 * equivalent to put_and_wait_on_page_locked(page, TASK_UNINTERRUPTIBLE) except
1438 * this can be called without taking a reference on the page. Instead this
1439 * should be called while holding the ptl for the migration entry referencing
1440 * the page.
1441 *
1442 * Returns after unmapping and unlocking the pte/ptl with pte_unmap_unlock().
1443 *
1444 * This follows the same logic as wait_on_page_bit_common() so see the comments
1445 * there.
1446 */
> 1447 void migration_entry_wait_on_locked(struct folio *folio, pte_t *ptep,
1448 spinlock_t *ptl)
1449 {
1450 struct wait_page_queue wait_page;
1451 wait_queue_entry_t *wait = &wait_page.wait;
1452 bool thrashing = false;
1453 bool delayacct = false;
1454 unsigned long pflags;
1455 wait_queue_head_t *q;
1456
1457 q = folio_waitqueue(folio);
1458 if (!folio_test_uptodate(folio) && folio_test_workingset(folio)) {
1459 if (!folio_test_swapbacked(folio)) {
1460 delayacct_thrashing_start();
1461 delayacct = true;
1462 }
1463 psi_memstall_enter(&pflags);
1464 thrashing = true;
1465 }
1466
1467 init_wait(wait);
1468 wait->func = wake_page_function;
1469 wait_page.folio = folio;
1470 wait_page.bit_nr = PG_locked;
1471 wait->flags = 0;
1472
1473 spin_lock_irq(&q->lock);
1474 folio_set_waiters(folio);
1475 if (!folio_trylock_flag(folio, PG_locked, wait))
1476 __add_wait_queue_entry_tail(q, wait);
1477 spin_unlock_irq(&q->lock);
1478
1479 /*
1480 * If a migration entry exists for the page the migration path must hold
1481 * a valid reference to the page, and it must take the ptl to remove the
1482 * migration entry. So the page is valid until the ptl is dropped.
1483 */
1484 if (ptep)
1485 pte_unmap_unlock(ptep, ptl);
1486 else
1487 spin_unlock(ptl);
1488
1489 for (;;) {
1490 unsigned int flags;
1491
1492 set_current_state(TASK_UNINTERRUPTIBLE);
1493
1494 /* Loop until we've been woken or interrupted */
1495 flags = smp_load_acquire(&wait->flags);
1496 if (!(flags & WQ_FLAG_WOKEN)) {
1497 if (signal_pending_state(TASK_UNINTERRUPTIBLE, current))
1498 break;
1499
1500 io_schedule();
1501 continue;
1502 }
1503 break;
1504 }
1505
1506 finish_wait(q, wait);
1507
1508 if (thrashing) {
1509 if (delayacct)
1510 delayacct_thrashing_end();
1511 psi_memstall_leave(&pflags);
1512 }
1513 }
1514 #endif
1515
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
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