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Message-ID: <202410291853.lBOeTPTK-lkp@intel.com>
Date: Tue, 29 Oct 2024 18:24:19 +0800
From: kernel test robot <lkp@...el.com>
To: Zi Yan <ziy@...dia.com>, linux-mm@...ck.org,
"Matthew Wilcox (Oracle)" <willy@...radead.org>
Cc: llvm@...ts.linux.dev, oe-kbuild-all@...ts.linux.dev,
Ryan Roberts <ryan.roberts@....com>,
Hugh Dickins <hughd@...gle.com>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
David Hildenbrand <david@...hat.com>,
Yang Shi <yang@...amperecomputing.com>,
Miaohe Lin <linmiaohe@...wei.com>,
Kefeng Wang <wangkefeng.wang@...wei.com>,
Yu Zhao <yuzhao@...gle.com>, John Hubbard <jhubbard@...dia.com>,
linux-kernel@...r.kernel.org, Zi Yan <ziy@...dia.com>
Subject: Re: [PATCH v1 1/3] mm/huge_memory: buddy allocator like folio_split()
Hi Zi,
kernel test robot noticed the following build warnings:
[auto build test WARNING on akpm-mm/mm-everything]
[also build test WARNING on next-20241029]
[cannot apply to linus/master v6.12-rc5]
[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/Zi-Yan/mm-huge_memory-buddy-allocator-like-folio_split/20241029-021200
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/r/20241028180932.1319265-2-ziy%40nvidia.com
patch subject: [PATCH v1 1/3] mm/huge_memory: buddy allocator like folio_split()
config: x86_64-kexec (https://download.01.org/0day-ci/archive/20241029/202410291853.lBOeTPTK-lkp@intel.com/config)
compiler: clang version 19.1.2 (https://github.com/llvm/llvm-project 7ba7d8e2f7b6445b60679da826210cdde29eaf8b)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241029/202410291853.lBOeTPTK-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/202410291853.lBOeTPTK-lkp@intel.com/
All warnings (new ones prefixed by >>):
In file included from mm/huge_memory.c:8:
In file included from include/linux/mm.h:2213:
include/linux/vmstat.h:504:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
504 | return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
| ~~~~~~~~~~~~~~~~~~~~~ ^
505 | item];
| ~~~~
include/linux/vmstat.h:511:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
511 | return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
| ~~~~~~~~~~~~~~~~~~~~~ ^
512 | NR_VM_NUMA_EVENT_ITEMS +
| ~~~~~~~~~~~~~~~~~~~~~~
include/linux/vmstat.h:518:36: warning: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
518 | return node_stat_name(NR_LRU_BASE + lru) + 3; // skip "nr_"
| ~~~~~~~~~~~ ^ ~~~
include/linux/vmstat.h:524:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
524 | return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
| ~~~~~~~~~~~~~~~~~~~~~ ^
525 | NR_VM_NUMA_EVENT_ITEMS +
| ~~~~~~~~~~~~~~~~~~~~~~
In file included from mm/huge_memory.c:18:
include/linux/mm_inline.h:47:41: warning: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
47 | __mod_lruvec_state(lruvec, NR_LRU_BASE + lru, nr_pages);
| ~~~~~~~~~~~ ^ ~~~
include/linux/mm_inline.h:49:22: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
49 | NR_ZONE_LRU_BASE + lru, nr_pages);
| ~~~~~~~~~~~~~~~~ ^ ~~~
>> mm/huge_memory.c:3342:6: warning: variable 'nr_dropped' set but not used [-Wunused-but-set-variable]
3342 | int nr_dropped = 0;
| ^
mm/huge_memory.c:3806:12: warning: unused function 'folio_split' [-Wunused-function]
3806 | static int folio_split(struct folio *folio, unsigned int new_order,
| ^~~~~~~~~~~
8 warnings generated.
vim +/nr_dropped +3342 mm/huge_memory.c
3292
3293 #define for_each_folio_until_end_safe(iter, iter2, start, end) \
3294 for (iter = start, iter2 = folio_next(start); \
3295 iter != end; \
3296 iter = iter2, iter2 = folio_next(iter2))
3297
3298 /*
3299 * It splits a @folio (without mapping) to lower order smaller folios in two
3300 * ways.
3301 * 1. uniform split: the given @folio into multiple @new_order small folios,
3302 * where all small folios have the same order. This is done when
3303 * uniform_split is true.
3304 * 2. buddy allocator like split: the given @folio is split into half and one
3305 * of the half (containing the given page) is split into half until the
3306 * given @page's order becomes @new_order. This is done when uniform_split is
3307 * false.
3308 *
3309 * The high level flow for these two methods are:
3310 * 1. uniform split: a single __split_folio_to_order() is called to split the
3311 * @folio into @new_order, then we traverse all the resulting folios one by
3312 * one in PFN ascending order and perform stats, unfreeze, adding to list,
3313 * and file mapping index operations.
3314 * 2. buddy allocator like split: in general, folio_order - @new_order calls to
3315 * __split_folio_to_order() are called in the for loop to split the @folio
3316 * to one lower order at a time. The resulting small folios are processed
3317 * like what is done during the traversal in 1, except the one containing
3318 * @page, which is split in next for loop.
3319 *
3320 * After splitting, the caller's folio reference will be transferred to the
3321 * folio containing @page. The other folios may be freed if they are not mapped.
3322 *
3323 * In terms of locking, after splitting,
3324 * 1. uniform split leaves @page (or the folio contains it) locked;
3325 * 2. buddy allocator like split leaves @folio locked.
3326 *
3327 * If @list is null, tail pages will be added to LRU list, otherwise, to @list.
3328 */
3329 static int __folio_split_without_mapping(struct folio *folio, int new_order,
3330 struct page *page, struct list_head *list, pgoff_t end,
3331 struct xa_state *xas, struct address_space *mapping,
3332 bool uniform_split)
3333 {
3334 struct lruvec *lruvec;
3335 struct address_space *swap_cache = NULL;
3336 struct folio *origin_folio = folio;
3337 struct folio *next_folio = folio_next(folio);
3338 struct folio *new_folio;
3339 struct folio *next;
3340 int order = folio_order(folio);
3341 int split_order = order - 1;
> 3342 int nr_dropped = 0;
3343
3344 if (folio_test_anon(folio) && folio_test_swapcache(folio)) {
3345 if (!uniform_split)
3346 return -EINVAL;
3347
3348 swap_cache = swap_address_space(folio->swap);
3349 xa_lock(&swap_cache->i_pages);
3350 }
3351
3352 if (folio_test_anon(folio))
3353 mod_mthp_stat(order, MTHP_STAT_NR_ANON, -1);
3354
3355 /* lock lru list/PageCompound, ref frozen by page_ref_freeze */
3356 lruvec = folio_lruvec_lock(folio);
3357
3358 /*
3359 * split to new_order one order at a time. For uniform split,
3360 * intermediate orders are skipped
3361 */
3362 for (split_order = order - 1; split_order >= new_order; split_order--) {
3363 int old_order = folio_order(folio);
3364 struct folio *release;
3365 struct folio *end_folio = folio_next(folio);
3366 int status;
3367
3368 if (folio_test_anon(folio) && split_order == 1)
3369 continue;
3370 if (uniform_split && split_order != new_order)
3371 continue;
3372
3373 if (mapping) {
3374 /*
3375 * uniform split has xas_split_alloc() called before
3376 * irq is disabled, since xas_nomem() might not be
3377 * able to allocate enough memory.
3378 */
3379 if (uniform_split)
3380 xas_split(xas, folio, old_order);
3381 else {
3382 xas_set_order(xas, folio->index, split_order);
3383 xas_set_err(xas, -ENOMEM);
3384 if (xas_nomem(xas, 0))
3385 xas_split(xas, folio, old_order);
3386 else
3387 return -ENOMEM;
3388 }
3389 }
3390
3391 split_page_memcg(&folio->page, old_order, split_order);
3392 split_page_owner(&folio->page, old_order, split_order);
3393 pgalloc_tag_split(folio, old_order, split_order);
3394
3395 status = __split_folio_to_order(folio, split_order);
3396
3397 if (status < 0)
3398 return status;
3399
3400 /*
3401 * Iterate through after-split folios and perform related
3402 * operations. But in buddy allocator like split, the folio
3403 * containing the specified page is skipped until its order
3404 * is new_order, since the folio will be worked on in next
3405 * iteration.
3406 */
3407 for_each_folio_until_end_safe(release, next, folio, end_folio) {
3408 if (page_in_folio_offset(page, release) >= 0) {
3409 folio = release;
3410 if (split_order != new_order)
3411 continue;
3412 }
3413 if (folio_test_anon(release))
3414 mod_mthp_stat(folio_order(release),
3415 MTHP_STAT_NR_ANON, 1);
3416
3417 /*
3418 * Unfreeze refcount first. Additional reference from
3419 * page cache.
3420 */
3421 folio_ref_unfreeze(release,
3422 1 + ((!folio_test_anon(origin_folio) ||
3423 folio_test_swapcache(origin_folio)) ?
3424 folio_nr_pages(release) : 0));
3425
3426 if (release != origin_folio)
3427 lru_add_page_tail(origin_folio, &release->page,
3428 lruvec, list);
3429
3430 /* Some pages can be beyond EOF: drop them from page cache */
3431 if (release->index >= end) {
3432 if (shmem_mapping(origin_folio->mapping))
3433 nr_dropped++;
3434 else if (folio_test_clear_dirty(release))
3435 folio_account_cleaned(release,
3436 inode_to_wb(origin_folio->mapping->host));
3437 __filemap_remove_folio(release, NULL);
3438 folio_put(release);
3439 } else if (!folio_test_anon(release)) {
3440 __xa_store(&origin_folio->mapping->i_pages,
3441 release->index, &release->page, 0);
3442 } else if (swap_cache) {
3443 __xa_store(&swap_cache->i_pages,
3444 swap_cache_index(release->swap),
3445 &release->page, 0);
3446 }
3447 }
3448 }
3449
3450 unlock_page_lruvec(lruvec);
3451
3452 if (folio_test_anon(origin_folio)) {
3453 if (folio_test_swapcache(origin_folio))
3454 xa_unlock(&swap_cache->i_pages);
3455 } else
3456 xa_unlock(&mapping->i_pages);
3457
3458 /* Caller disabled irqs, so they are still disabled here */
3459 local_irq_enable();
3460
3461 remap_page(origin_folio, 1 << order,
3462 folio_test_anon(origin_folio) ?
3463 RMP_USE_SHARED_ZEROPAGE : 0);
3464
3465 /*
3466 * At this point, folio should contain the specified page, so that it
3467 * will be left to the caller to unlock it.
3468 */
3469 for_each_folio_until_end_safe(new_folio, next, origin_folio, next_folio) {
3470 if (uniform_split && new_folio == folio)
3471 continue;
3472 if (!uniform_split && new_folio == origin_folio)
3473 continue;
3474
3475 folio_unlock(new_folio);
3476 /*
3477 * Subpages may be freed if there wasn't any mapping
3478 * like if add_to_swap() is running on a lru page that
3479 * had its mapping zapped. And freeing these pages
3480 * requires taking the lru_lock so we do the put_page
3481 * of the tail pages after the split is complete.
3482 */
3483 free_page_and_swap_cache(&new_folio->page);
3484 }
3485 return 0;
3486 }
3487
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
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