On 2024/3/1 5:20, Matthew Wilcox (Oracle) wrote:
> Removes two calls to compound_head(). Move the prototype to
> internal.h; we definitely don't want code outside mm using it.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> ---
> include/linux/mm.h | 1 -
> mm/hwpoison-inject.c | 11 ++++++-----
> mm/internal.h | 1 +
> mm/memory-failure.c | 15 ++++++++++-----
> 4 files changed, 17 insertions(+), 11 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 03e4841673d7..184f57cdab60 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -3962,7 +3962,6 @@ int mf_dax_kill_procs(struct address_space *mapping, pgoff_t index,
> extern int memory_failure(unsigned long pfn, int flags);
> extern void memory_failure_queue_kick(int cpu);
> extern int unpoison_memory(unsigned long pfn);
> -extern void shake_page(struct page *p);
> extern atomic_long_t num_poisoned_pages __read_mostly;
> extern int soft_offline_page(unsigned long pfn, int flags);
> #ifdef CONFIG_MEMORY_FAILURE
> diff --git a/mm/hwpoison-inject.c b/mm/hwpoison-inject.c
> index d0548e382b6b..c9d653f51e45 100644
> --- a/mm/hwpoison-inject.c
> +++ b/mm/hwpoison-inject.c
> @@ -15,7 +15,7 @@ static int hwpoison_inject(void *data, u64 val)
> {
> unsigned long pfn = val;
> struct page *p;
> - struct page *hpage;
> + struct folio *folio;
> int err;
>
> if (!capable(CAP_SYS_ADMIN))
> @@ -25,16 +25,17 @@ static int hwpoison_inject(void *data, u64 val)
> return -ENXIO;
>
> p = pfn_to_page(pfn);
> - hpage = compound_head(p);
> + folio = page_folio(p);
>
> if (!hwpoison_filter_enable)
> goto inject;
>
> - shake_page(hpage);
> + shake_folio(folio);
> /*
> * This implies unable to support non-LRU pages except free page.
> */
> - if (!PageLRU(hpage) && !PageHuge(p) && !is_free_buddy_page(p))
> + if (!folio_test_lru(folio) && !folio_test_hugetlb(folio) &&
> + !is_free_buddy_page(p))
> return 0;
>
> /*
> @@ -42,7 +43,7 @@ static int hwpoison_inject(void *data, u64 val)
> * the targeted owner (or on a free page).
> * memory_failure() will redo the check reliably inside page lock.
> */
> - err = hwpoison_filter(hpage);
> + err = hwpoison_filter(&folio->page);
> if (err)
> return 0;
>
> diff --git a/mm/internal.h b/mm/internal.h
> index 13f4d6ccccdf..b900730f43c0 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -855,6 +855,7 @@ static inline int find_next_best_node(int node, nodemask_t *used_node_mask)
> /*
> * mm/memory-failure.c
> */
> +void shake_folio(struct folio *folio);
> extern int hwpoison_filter(struct page *p);
>
> extern u32 hwpoison_filter_dev_major;
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 40a8964954e5..27dc21063552 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -358,20 +358,25 @@ static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags)
> * Unknown page type encountered. Try to check whether it can turn PageLRU by
> * lru_add_drain_all.
> */
> -void shake_page(struct page *p)
> +void shake_folio(struct folio *folio)
It might not be a good idea to convert shake_page() into shake_folio(). shake_page() can
be called without holding page refcnt. So the below race could happen:
hwpoison_inject
folio = page_folio(p); --> assume p is 4k page [1]
shake_folio(folio)
folio_test_slab(folio)
test_bit(PG_slab, folio_flags(folio, FOLIO_PF_NO_TAIL) [2]
VM_BUG_ON_PGFLAGS(PageTail(page), page) in folio_flags
Between [1] and [2], page can become PageTail of a THP. So the VM_BUG_ON_PGFLAGS will trigger.
Or am I miss something?
Thanks.
> {
> - if (PageHuge(p))
> + if (folio_test_hugetlb(folio))
> return;
> /*
> * TODO: Could shrink slab caches here if a lightweight range-based
> * shrinker will be available.
> */
> - if (PageSlab(p))
> + if (folio_test_slab(folio))
> return;
>
> lru_add_drain_all();
> }
> -EXPORT_SYMBOL_GPL(shake_page);
> +EXPORT_SYMBOL_GPL(shake_folio);
> +
> +static void shake_page(struct page *page)
> +{
> + shake_folio(page_folio(page));
> +}
>
> static unsigned long dev_pagemap_mapping_shift(struct vm_area_struct *vma,
> unsigned long address)
> @@ -1639,7 +1644,7 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
> * shake_page() again to ensure that it's flushed.
> */
> if (mlocked)
> - shake_page(hpage);
> + shake_folio(folio);
>
> /*
> * Now that the dirty bit has been propagated to the
>
