diff options
Diffstat (limited to 'mm')
-rw-r--r-- | mm/filemap.c | 23 | ||||
-rw-r--r-- | mm/migrate.c | 13 | ||||
-rw-r--r-- | mm/mremap.c | 23 |
3 files changed, 43 insertions, 16 deletions
diff --git a/mm/filemap.c b/mm/filemap.c index f0ae9a6308cb..385759c4ce4b 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2028,7 +2028,7 @@ find_page: page = find_get_page(mapping, index); if (!page) { - if (iocb->ki_flags & IOCB_NOWAIT) + if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_NOIO)) goto would_block; page_cache_sync_readahead(mapping, ra, filp, @@ -2038,6 +2038,10 @@ find_page: goto no_cached_page; } if (PageReadahead(page)) { + if (iocb->ki_flags & IOCB_NOIO) { + put_page(page); + goto out; + } page_cache_async_readahead(mapping, ra, filp, page, index, last_index - index); @@ -2160,6 +2164,11 @@ page_not_up_to_date_locked: } readpage: + if (iocb->ki_flags & IOCB_NOIO) { + unlock_page(page); + put_page(page); + goto would_block; + } /* * A previous I/O error may have been due to temporary * failures, eg. multipath errors. @@ -2249,9 +2258,19 @@ EXPORT_SYMBOL_GPL(generic_file_buffered_read); * * This is the "read_iter()" routine for all filesystems * that can use the page cache directly. + * + * The IOCB_NOWAIT flag in iocb->ki_flags indicates that -EAGAIN shall + * be returned when no data can be read without waiting for I/O requests + * to complete; it doesn't prevent readahead. + * + * The IOCB_NOIO flag in iocb->ki_flags indicates that no new I/O + * requests shall be made for the read or for readahead. When no data + * can be read, -EAGAIN shall be returned. When readahead would be + * triggered, a partial, possibly empty read shall be returned. + * * Return: * * number of bytes copied, even for partial reads - * * negative error code if nothing was read + * * negative error code (or 0 if IOCB_NOIO) if nothing was read */ ssize_t generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter) diff --git a/mm/migrate.c b/mm/migrate.c index f37729673558..40cd7016ae6f 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1161,21 +1161,10 @@ out: } /* - * gcc 4.7 and 4.8 on arm get an ICEs when inlining unmap_and_move(). Work - * around it. - */ -#if defined(CONFIG_ARM) && \ - defined(GCC_VERSION) && GCC_VERSION < 40900 && GCC_VERSION >= 40700 -#define ICE_noinline noinline -#else -#define ICE_noinline -#endif - -/* * Obtain the lock on page, remove all ptes and migrate the page * to the newly allocated page in newpage. */ -static ICE_noinline int unmap_and_move(new_page_t get_new_page, +static int unmap_and_move(new_page_t get_new_page, free_page_t put_new_page, unsigned long private, struct page *page, int force, enum migrate_mode mode, diff --git a/mm/mremap.c b/mm/mremap.c index 5dd572d57ca9..6b153dc05fe4 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -206,9 +206,28 @@ static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr, /* * The destination pmd shouldn't be established, free_pgtables() - * should have release it. + * should have released it. + * + * However, there's a case during execve() where we use mremap + * to move the initial stack, and in that case the target area + * may overlap the source area (always moving down). + * + * If everything is PMD-aligned, that works fine, as moving + * each pmd down will clear the source pmd. But if we first + * have a few 4kB-only pages that get moved down, and then + * hit the "now the rest is PMD-aligned, let's do everything + * one pmd at a time", we will still have the old (now empty + * of any 4kB pages, but still there) PMD in the page table + * tree. + * + * Warn on it once - because we really should try to figure + * out how to do this better - but then say "I won't move + * this pmd". + * + * One alternative might be to just unmap the target pmd at + * this point, and verify that it really is empty. We'll see. */ - if (WARN_ON(!pmd_none(*new_pmd))) + if (WARN_ON_ONCE(!pmd_none(*new_pmd))) return false; /* |