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    SubjectRe: [PATCH 04/16] page-flags: define PG_locked behavior on compound pages
    Date
    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@linux.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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