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Message-ID: <55157314.5080008@samsung.com>
Date: Fri, 27 Mar 2015 16:11:16 +0100
From: Mateusz Krawczuk <m.krawczuk@...sung.com>
To: linux-kernel@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Subject: Re: [PATCH 04/16] page-flags: define PG_locked behavior on compound
pages
Hi!
This patch breaks build of linux next since 2015-03-25 on arm using
exynos_defconfig with arm-linux-gnueabi-linaro_4.7.4-2014.04,
arm-linux-gnueabi-linaro_4.8.3-2014.04 and
arm-linux-gnueabi-4.7.3-12ubuntu1(from ubuntu 14.04 lts). Compiler shows
this error message:
mm/migrate.c: In function ‘migrate_pages’:
mm/migrate.c:1148:1: internal compiler error: in push_minipool_fix, at
config/arm/arm.c:13500
Please submit a full bug report,
with preprocessed source if appropriate.
See <file:///usr/share/doc/gcc-4.7/README.Bugs> for instructions.
It builds fine with arm-linux-gnueabi-linaro_4.9.1-2014.07.
Best Regards
Mateusz Krawczuk
Samsung R&D Institute Poland
dniu 19.03.2015 o 18:08, Kirill A. Shutemov pisze:
> lock_page() must operate on the whole compound page. It doesn't make
> much sense to lock part of compound page. Change code to use head page's
> PG_locked, if tail page is passed.
>
> This patch also get rid of custom helprer functions --
> __set_page_locked() and __clear_page_locked(). They replaced with
> helpers generated by __SETPAGEFLAG/__CLEARPAGEFLAG. Tail pages to these
> helper would trigger VM_BUG_ON().
>
> SLUB uses PG_locked as a bit spin locked. IIUC, tail pages should never
> appear there. VM_BUG_ON() is added to make sure that this assumption is
> correct.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> ---
> fs/cifs/file.c | 8 ++++----
> include/linux/page-flags.h | 2 +-
> include/linux/pagemap.h | 25 ++++++++-----------------
> mm/filemap.c | 15 +++++++++------
> mm/ksm.c | 2 +-
> mm/memory-failure.c | 2 +-
> mm/migrate.c | 2 +-
> mm/shmem.c | 4 ++--
> mm/slub.c | 2 ++
> mm/swap_state.c | 4 ++--
> mm/vmscan.c | 4 ++--
> mm/zswap.c | 4 ++--
> 12 files changed, 35 insertions(+), 39 deletions(-)
>
> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> index ca30c391a894..b9fd85dfee9b 100644
> --- a/fs/cifs/file.c
> +++ b/fs/cifs/file.c
> @@ -3413,13 +3413,13 @@ readpages_get_pages(struct address_space *mapping, struct list_head *page_list,
> * should have access to this page, we're safe to simply set
> * PG_locked without checking it first.
> */
> - __set_page_locked(page);
> + __SetPageLocked(page);
> rc = add_to_page_cache_locked(page, mapping,
> page->index, GFP_KERNEL);
>
> /* give up if we can't stick it in the cache */
> if (rc) {
> - __clear_page_locked(page);
> + __ClearPageLocked(page);
> return rc;
> }
>
> @@ -3440,10 +3440,10 @@ readpages_get_pages(struct address_space *mapping, struct list_head *page_list,
> if (*bytes + PAGE_CACHE_SIZE > rsize)
> break;
>
> - __set_page_locked(page);
> + __SetPageLocked(page);
> if (add_to_page_cache_locked(page, mapping, page->index,
> GFP_KERNEL)) {
> - __clear_page_locked(page);
> + __ClearPageLocked(page);
> break;
> }
> list_move_tail(&page->lru, tmplist);
> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
> index 32ea62c0ad30..10bdde20b14c 100644
> --- a/include/linux/page-flags.h
> +++ b/include/linux/page-flags.h
> @@ -269,7 +269,7 @@ static inline struct page *compound_head_fast(struct page *page)
> return page;
> }
>
> -TESTPAGEFLAG(Locked, locked, ANY)
> +__PAGEFLAG(Locked, locked, NO_TAIL)
> PAGEFLAG(Error, error, ANY) TESTCLEARFLAG(Error, error, ANY)
> PAGEFLAG(Referenced, referenced, ANY) TESTCLEARFLAG(Referenced, referenced, ANY)
> __SETPAGEFLAG(Referenced, referenced, ANY)
> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index 4b3736f7065c..7c3790764795 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -426,18 +426,9 @@ extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
> unsigned int flags);
> extern void unlock_page(struct page *page);
>
> -static inline void __set_page_locked(struct page *page)
> -{
> - __set_bit(PG_locked, &page->flags);
> -}
> -
> -static inline void __clear_page_locked(struct page *page)
> -{
> - __clear_bit(PG_locked, &page->flags);
> -}
> -
> static inline int trylock_page(struct page *page)
> {
> + page = compound_head(page);
> return (likely(!test_and_set_bit_lock(PG_locked, &page->flags)));
> }
>
> @@ -490,9 +481,9 @@ extern int wait_on_page_bit_killable_timeout(struct page *page,
>
> static inline int wait_on_page_locked_killable(struct page *page)
> {
> - if (PageLocked(page))
> - return wait_on_page_bit_killable(page, PG_locked);
> - return 0;
> + if (!PageLocked(page))
> + return 0;
> + return wait_on_page_bit_killable(compound_head(page), PG_locked);
> }
>
> extern wait_queue_head_t *page_waitqueue(struct page *page);
> @@ -511,7 +502,7 @@ static inline void wake_up_page(struct page *page, int bit)
> static inline void wait_on_page_locked(struct page *page)
> {
> if (PageLocked(page))
> - wait_on_page_bit(page, PG_locked);
> + wait_on_page_bit(compound_head(page), PG_locked);
> }
>
> /*
> @@ -656,17 +647,17 @@ int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask);
>
> /*
> * Like add_to_page_cache_locked, but used to add newly allocated pages:
> - * the page is new, so we can just run __set_page_locked() against it.
> + * the page is new, so we can just run __SetPageLocked() against it.
> */
> static inline int add_to_page_cache(struct page *page,
> struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask)
> {
> int error;
>
> - __set_page_locked(page);
> + __SetPageLocked(page);
> error = add_to_page_cache_locked(page, mapping, offset, gfp_mask);
> if (unlikely(error))
> - __clear_page_locked(page);
> + __ClearPageLocked(page);
> return error;
> }
>
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 12548d03c11d..467768d4263b 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -615,11 +615,11 @@ int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
> void *shadow = NULL;
> int ret;
>
> - __set_page_locked(page);
> + __SetPageLocked(page);
> ret = __add_to_page_cache_locked(page, mapping, offset,
> gfp_mask, &shadow);
> if (unlikely(ret))
> - __clear_page_locked(page);
> + __ClearPageLocked(page);
> else {
> /*
> * The page might have been evicted from cache only
> @@ -742,6 +742,7 @@ EXPORT_SYMBOL_GPL(add_page_wait_queue);
> */
> void unlock_page(struct page *page)
> {
> + page = compound_head(page);
> VM_BUG_ON_PAGE(!PageLocked(page), page);
> clear_bit_unlock(PG_locked, &page->flags);
> smp_mb__after_atomic();
> @@ -806,18 +807,20 @@ EXPORT_SYMBOL_GPL(page_endio);
> */
> void __lock_page(struct page *page)
> {
> - DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
> + struct page *page_head = compound_head(page);
> + DEFINE_WAIT_BIT(wait, &page_head->flags, PG_locked);
>
> - __wait_on_bit_lock(page_waitqueue(page), &wait, bit_wait_io,
> + __wait_on_bit_lock(page_waitqueue(page_head), &wait, bit_wait_io,
> TASK_UNINTERRUPTIBLE);
> }
> EXPORT_SYMBOL(__lock_page);
>
> int __lock_page_killable(struct page *page)
> {
> - DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
> + struct page *page_head = compound_head(page);
> + DEFINE_WAIT_BIT(wait, &page_head->flags, PG_locked);
>
> - return __wait_on_bit_lock(page_waitqueue(page), &wait,
> + return __wait_on_bit_lock(page_waitqueue(page_head), &wait,
> bit_wait_io, TASK_KILLABLE);
> }
> EXPORT_SYMBOL_GPL(__lock_page_killable);
> diff --git a/mm/ksm.c b/mm/ksm.c
> index 4162dce2eb44..23138e99a531 100644
> --- a/mm/ksm.c
> +++ b/mm/ksm.c
> @@ -1884,7 +1884,7 @@ struct page *ksm_might_need_to_copy(struct page *page,
>
> SetPageDirty(new_page);
> __SetPageUptodate(new_page);
> - __set_page_locked(new_page);
> + __SetPageLocked(new_page);
> }
>
> return new_page;
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index d487f8dc6d39..399eee44d13d 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1136,7 +1136,7 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
> /*
> * We ignore non-LRU pages for good reasons.
> * - PG_locked is only well defined for LRU pages and a few others
> - * - to avoid races with __set_page_locked()
> + * - to avoid races with __SetPageLocked()
> * - to avoid races with __SetPageSlab*() (and more non-atomic ops)
> * The check (unnecessarily) ignores LRU pages being isolated and
> * walked by the page reclaim code, however that's not a big loss.
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 6aa9a4222ea9..114602a68111 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1734,7 +1734,7 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
> flush_tlb_range(vma, mmun_start, mmun_end);
>
> /* Prepare a page as a migration target */
> - __set_page_locked(new_page);
> + __SetPageLocked(new_page);
> SetPageSwapBacked(new_page);
>
> /* anon mapping, we can simply copy page->mapping to the new page: */
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 80b360c7bcd1..2e2b943c8e62 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -981,7 +981,7 @@ static int shmem_replace_page(struct page **pagep, gfp_t gfp,
> copy_highpage(newpage, oldpage);
> flush_dcache_page(newpage);
>
> - __set_page_locked(newpage);
> + __SetPageLocked(newpage);
> SetPageUptodate(newpage);
> SetPageSwapBacked(newpage);
> set_page_private(newpage, swap_index);
> @@ -1173,7 +1173,7 @@ repeat:
> }
>
> __SetPageSwapBacked(page);
> - __set_page_locked(page);
> + __SetPageLocked(page);
> if (sgp == SGP_WRITE)
> __SetPageReferenced(page);
>
> diff --git a/mm/slub.c b/mm/slub.c
> index 2584d4ff02eb..f33ae2b7a5e7 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -338,11 +338,13 @@ static inline int oo_objects(struct kmem_cache_order_objects x)
> */
> static __always_inline void slab_lock(struct page *page)
> {
> + VM_BUG_ON_PAGE(PageTail(page), page);
> bit_spin_lock(PG_locked, &page->flags);
> }
>
> static __always_inline void slab_unlock(struct page *page)
> {
> + VM_BUG_ON_PAGE(PageTail(page), page);
> __bit_spin_unlock(PG_locked, &page->flags);
> }
>
> diff --git a/mm/swap_state.c b/mm/swap_state.c
> index 405923f77334..d1c4a25b4362 100644
> --- a/mm/swap_state.c
> +++ b/mm/swap_state.c
> @@ -357,7 +357,7 @@ struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
> }
>
> /* May fail (-ENOMEM) if radix-tree node allocation failed. */
> - __set_page_locked(new_page);
> + __SetPageLocked(new_page);
> SetPageSwapBacked(new_page);
> err = __add_to_swap_cache(new_page, entry);
> if (likely(!err)) {
> @@ -371,7 +371,7 @@ struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
> }
> radix_tree_preload_end();
> ClearPageSwapBacked(new_page);
> - __clear_page_locked(new_page);
> + __ClearPageLocked(new_page);
> /*
> * add_to_swap_cache() doesn't return -EEXIST, so we can safely
> * clear SWAP_HAS_CACHE flag.
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 260c413d39cd..dc6cd51577a6 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1062,7 +1062,7 @@ unmap:
> VM_BUG_ON_PAGE(PageSwapCache(page), page);
> if (!page_freeze_refs(page, 1))
> goto keep_locked;
> - __clear_page_locked(page);
> + __ClearPageLocked(page);
> count_vm_event(PGLAZYFREED);
> goto free_it;
> }
> @@ -1174,7 +1174,7 @@ unmap:
> * we obviously don't have to worry about waking up a process
> * waiting on the page lock, because there are no references.
> */
> - __clear_page_locked(page);
> + __ClearPageLocked(page);
> free_it:
> nr_reclaimed++;
>
> diff --git a/mm/zswap.c b/mm/zswap.c
> index 4249e82ff934..f8583f1fc938 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -490,7 +490,7 @@ static int zswap_get_swap_cache_page(swp_entry_t entry,
> }
>
> /* May fail (-ENOMEM) if radix-tree node allocation failed. */
> - __set_page_locked(new_page);
> + __SetPageLocked(new_page);
> SetPageSwapBacked(new_page);
> err = __add_to_swap_cache(new_page, entry);
> if (likely(!err)) {
> @@ -501,7 +501,7 @@ static int zswap_get_swap_cache_page(swp_entry_t entry,
> }
> radix_tree_preload_end();
> ClearPageSwapBacked(new_page);
> - __clear_page_locked(new_page);
> + __ClearPageLocked(new_page);
> /*
> * add_to_swap_cache() doesn't return -EEXIST, so we can safely
> * clear SWAP_HAS_CACHE flag.
>
--
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