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Date: Thu, 21 Sep 2023 19:05:40 +0800
From: kernel test robot <lkp@...el.com>
To: Yosry Ahmed <yosryahmed@...gle.com>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: oe-kbuild-all@...ts.linux.dev,
Linux Memory Management List <linux-mm@...ck.org>,
Johannes Weiner <hannes@...xchg.org>,
Michal Hocko <mhocko@...nel.org>,
Roman Gushchin <roman.gushchin@...ux.dev>,
Shakeel Butt <shakeelb@...gle.com>,
Muchun Song <muchun.song@...ux.dev>,
Ivan Babrou <ivan@...udflare.com>, Tejun Heo <tj@...nel.org>,
Michal Koutný <mkoutny@...e.com>,
Waiman Long <longman@...hat.com>, kernel-team@...udflare.com,
Wei Xu <weixugc@...gle.com>, Greg Thelen <gthelen@...gle.com>,
cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
Yosry Ahmed <yosryahmed@...gle.com>
Subject: Re: [PATCH 4/5] mm: workingset: move the stats flush into
workingset_test_recent()
Hi Yosry,
kernel test robot noticed the following build errors:
[auto build test ERROR on akpm-mm/mm-everything]
url: https://github.com/intel-lab-lkp/linux/commits/Yosry-Ahmed/mm-memcg-change-flush_next_time-to-flush_last_time/20230921-161246
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/r/20230921081057.3440885-5-yosryahmed%40google.com
patch subject: [PATCH 4/5] mm: workingset: move the stats flush into workingset_test_recent()
config: powerpc-allnoconfig (https://download.01.org/0day-ci/archive/20230921/202309211829.Efuqg8NE-lkp@intel.com/config)
compiler: powerpc-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230921/202309211829.Efuqg8NE-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@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202309211829.Efuqg8NE-lkp@intel.com/
All errors (new ones prefixed by >>):
mm/workingset.c: In function 'workingset_test_recent':
>> mm/workingset.c:461:32: error: invalid use of undefined type 'struct mem_cgroup'
461 | css_get(&eviction_memcg->css);
| ^~
vim +461 mm/workingset.c
405
406 /**
407 * workingset_test_recent - tests if the shadow entry is for a folio that was
408 * recently evicted. Also fills in @workingset with the value unpacked from
409 * shadow.
410 * @shadow: the shadow entry to be tested.
411 * @file: whether the corresponding folio is from the file lru.
412 * @workingset: where the workingset value unpacked from shadow should
413 * be stored.
414 *
415 * Return: true if the shadow is for a recently evicted folio; false otherwise.
416 */
417 bool workingset_test_recent(void *shadow, bool file, bool *workingset)
418 {
419 struct mem_cgroup *eviction_memcg;
420 struct lruvec *eviction_lruvec;
421 unsigned long refault_distance;
422 unsigned long workingset_size;
423 unsigned long refault;
424 int memcgid;
425 struct pglist_data *pgdat;
426 unsigned long eviction;
427
428 rcu_read_lock();
429
430 if (lru_gen_enabled()) {
431 bool recent = lru_gen_test_recent(shadow, file,
432 &eviction_lruvec, &eviction,
433 workingset);
434 rcu_read_unlock();
435 return recent;
436 }
437
438 unpack_shadow(shadow, &memcgid, &pgdat, &eviction, workingset);
439 eviction <<= bucket_order;
440
441 /*
442 * Look up the memcg associated with the stored ID. It might
443 * have been deleted since the folio's eviction.
444 *
445 * Note that in rare events the ID could have been recycled
446 * for a new cgroup that refaults a shared folio. This is
447 * impossible to tell from the available data. However, this
448 * should be a rare and limited disturbance, and activations
449 * are always speculative anyway. Ultimately, it's the aging
450 * algorithm's job to shake out the minimum access frequency
451 * for the active cache.
452 *
453 * XXX: On !CONFIG_MEMCG, this will always return NULL; it
454 * would be better if the root_mem_cgroup existed in all
455 * configurations instead.
456 */
457 eviction_memcg = mem_cgroup_from_id(memcgid);
458 if (!mem_cgroup_disabled() && !eviction_memcg)
459 return false;
460
> 461 css_get(&eviction_memcg->css);
462 rcu_read_unlock();
463
464 /* Flush stats (and potentially sleep) outside the RCU read section */
465 mem_cgroup_flush_stats_ratelimited();
466
467 eviction_lruvec = mem_cgroup_lruvec(eviction_memcg, pgdat);
468 refault = atomic_long_read(&eviction_lruvec->nonresident_age);
469
470 /*
471 * Calculate the refault distance
472 *
473 * The unsigned subtraction here gives an accurate distance
474 * across nonresident_age overflows in most cases. There is a
475 * special case: usually, shadow entries have a short lifetime
476 * and are either refaulted or reclaimed along with the inode
477 * before they get too old. But it is not impossible for the
478 * nonresident_age to lap a shadow entry in the field, which
479 * can then result in a false small refault distance, leading
480 * to a false activation should this old entry actually
481 * refault again. However, earlier kernels used to deactivate
482 * unconditionally with *every* reclaim invocation for the
483 * longest time, so the occasional inappropriate activation
484 * leading to pressure on the active list is not a problem.
485 */
486 refault_distance = (refault - eviction) & EVICTION_MASK;
487
488 /*
489 * Compare the distance to the existing workingset size. We
490 * don't activate pages that couldn't stay resident even if
491 * all the memory was available to the workingset. Whether
492 * workingset competition needs to consider anon or not depends
493 * on having free swap space.
494 */
495 workingset_size = lruvec_page_state(eviction_lruvec, NR_ACTIVE_FILE);
496 if (!file) {
497 workingset_size += lruvec_page_state(eviction_lruvec,
498 NR_INACTIVE_FILE);
499 }
500 if (mem_cgroup_get_nr_swap_pages(eviction_memcg) > 0) {
501 workingset_size += lruvec_page_state(eviction_lruvec,
502 NR_ACTIVE_ANON);
503 if (file) {
504 workingset_size += lruvec_page_state(eviction_lruvec,
505 NR_INACTIVE_ANON);
506 }
507 }
508
509 mem_cgroup_put(eviction_memcg);
510 return refault_distance <= workingset_size;
511 }
512
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
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