Commit 69bf4b6b authored by Linus Torvalds's avatar Linus Torvalds

Revert "mm: page cache: store only head pages in i_pages"

This reverts commit 5fd4ca2d.

Mikhail Gavrilov reports that it causes the VM_BUG_ON_PAGE() in
__delete_from_swap_cache() to trigger:

   page:ffffd6d34dff0000 refcount:1 mapcount:1 mapping:ffff97812323a689 index:0xfecec363
   anon
   flags: 0x17fffe00080034(uptodate|lru|active|swapbacked)
   raw: 0017fffe00080034 ffffd6d34c67c508 ffffd6d3504b8d48 ffff97812323a689
   raw: 00000000fecec363 0000000000000000 0000000100000000 ffff978433ace000
   page dumped because: VM_BUG_ON_PAGE(entry != page)
   page->mem_cgroup:ffff978433ace000
   ------------[ cut here ]------------
   kernel BUG at mm/swap_state.c:170!
   invalid opcode: 0000 [#1] SMP NOPTI
   CPU: 1 PID: 221 Comm: kswapd0 Not tainted 5.2.0-0.rc2.git0.1.fc31.x86_64 #1
   Hardware name: System manufacturer System Product Name/ROG STRIX X470-I GAMING, BIOS 2202 04/11/2019
   RIP: 0010:__delete_from_swap_cache+0x20d/0x240
   Code: 30 65 48 33 04 25 28 00 00 00 75 4a 48 83 c4 38 5b 5d 41 5c 41 5d 41 5e 41 5f c3 48 c7 c6 2f dc 0f 8a 48 89 c7 e8 93 1b fd ff <0f> 0b 48 c7 c6 a8 74 0f 8a e8 85 1b fd ff 0f 0b 48 c7 c6 a8 7d 0f
   RSP: 0018:ffffa982036e7980 EFLAGS: 00010046
   RAX: 0000000000000021 RBX: 0000000000000040 RCX: 0000000000000006
   RDX: 0000000000000000 RSI: 0000000000000086 RDI: ffff97843d657900
   RBP: 0000000000000001 R08: ffffa982036e7835 R09: 0000000000000535
   R10: ffff97845e21a46c R11: ffffa982036e7835 R12: ffff978426387120
   R13: 0000000000000000 R14: ffffd6d34dff0040 R15: ffffd6d34dff0000
   FS:  0000000000000000(0000) GS:ffff97843d640000(0000) knlGS:0000000000000000
   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
   CR2: 00002cba88ef5000 CR3: 000000078a97c000 CR4: 00000000003406e0
   Call Trace:
    delete_from_swap_cache+0x46/0xa0
    try_to_free_swap+0xbc/0x110
    swap_writepage+0x13/0x70
    pageout.isra.0+0x13c/0x350
    shrink_page_list+0xc14/0xdf0
    shrink_inactive_list+0x1e5/0x3c0
    shrink_node_memcg+0x202/0x760
    shrink_node+0xe0/0x470
    balance_pgdat+0x2d1/0x510
    kswapd+0x220/0x420
    kthread+0xfb/0x130
    ret_from_fork+0x22/0x40

and it's not immediately obvious why it happens.  It's too late in the
rc cycle to do anything but revert for now.

Link: https://lore.kernel.org/lkml/CABXGCsN9mYmBD-4GaaeW_NrDu+FDXLzr_6x+XNxfmFV6QkYCDg@mail.gmail.com/Reported-and-bisected-by: default avatarMikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Suggested-by: default avatarJan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Kirill Shutemov <kirill@shutemov.name>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 9fdb86c8
......@@ -333,19 +333,6 @@ static inline struct page *grab_cache_page_nowait(struct address_space *mapping,
mapping_gfp_mask(mapping));
}
static inline struct page *find_subpage(struct page *page, pgoff_t offset)
{
unsigned long mask;
if (PageHuge(page))
return page;
VM_BUG_ON_PAGE(PageTail(page), page);
mask = (1UL << compound_order(page)) - 1;
return page + (offset & mask);
}
struct page *find_get_entry(struct address_space *mapping, pgoff_t offset);
struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset);
unsigned find_get_entries(struct address_space *mapping, pgoff_t start,
......
......@@ -281,11 +281,11 @@ EXPORT_SYMBOL(delete_from_page_cache);
* @pvec: pagevec with pages to delete
*
* The function walks over mapping->i_pages and removes pages passed in @pvec
* from the mapping. The function expects @pvec to be sorted by page index
* and is optimised for it to be dense.
* from the mapping. The function expects @pvec to be sorted by page index.
* It tolerates holes in @pvec (mapping entries at those indices are not
* modified). The function expects only THP head pages to be present in the
* @pvec.
* @pvec and takes care to delete all corresponding tail pages from the
* mapping as well.
*
* The function expects the i_pages lock to be held.
*/
......@@ -294,44 +294,40 @@ static void page_cache_delete_batch(struct address_space *mapping,
{
XA_STATE(xas, &mapping->i_pages, pvec->pages[0]->index);
int total_pages = 0;
int i = 0;
int i = 0, tail_pages = 0;
struct page *page;
mapping_set_update(&xas, mapping);
xas_for_each(&xas, page, ULONG_MAX) {
if (i >= pagevec_count(pvec))
if (i >= pagevec_count(pvec) && !tail_pages)
break;
/* A swap/dax/shadow entry got inserted? Skip it. */
if (xa_is_value(page))
continue;
/*
* A page got inserted in our range? Skip it. We have our
* pages locked so they are protected from being removed.
* If we see a page whose index is higher than ours, it
* means our page has been removed, which shouldn't be
* possible because we're holding the PageLock.
*/
if (page != pvec->pages[i]) {
VM_BUG_ON_PAGE(page->index > pvec->pages[i]->index,
page);
continue;
}
WARN_ON_ONCE(!PageLocked(page));
if (page->index == xas.xa_index)
if (!tail_pages) {
/*
* Some page got inserted in our range? Skip it. We
* have our pages locked so they are protected from
* being removed.
*/
if (page != pvec->pages[i]) {
VM_BUG_ON_PAGE(page->index >
pvec->pages[i]->index, page);
continue;
}
WARN_ON_ONCE(!PageLocked(page));
if (PageTransHuge(page) && !PageHuge(page))
tail_pages = HPAGE_PMD_NR - 1;
page->mapping = NULL;
/* Leave page->index set: truncation lookup relies on it */
/*
* Move to the next page in the vector if this is a regular
* page or the index is of the last sub-page of this compound
* page.
*/
if (page->index + (1UL << compound_order(page)) - 1 ==
xas.xa_index)
/*
* Leave page->index set: truncation lookup relies
* upon it
*/
i++;
} else {
VM_BUG_ON_PAGE(page->index + HPAGE_PMD_NR - tail_pages
!= pvec->pages[i]->index, page);
tail_pages--;
}
xas_store(&xas, NULL);
total_pages++;
}
......@@ -1498,7 +1494,7 @@ EXPORT_SYMBOL(page_cache_prev_miss);
struct page *find_get_entry(struct address_space *mapping, pgoff_t offset)
{
XA_STATE(xas, &mapping->i_pages, offset);
struct page *page;
struct page *head, *page;
rcu_read_lock();
repeat:
......@@ -1513,19 +1509,25 @@ struct page *find_get_entry(struct address_space *mapping, pgoff_t offset)
if (!page || xa_is_value(page))
goto out;
if (!page_cache_get_speculative(page))
head = compound_head(page);
if (!page_cache_get_speculative(head))
goto repeat;
/* The page was split under us? */
if (compound_head(page) != head) {
put_page(head);
goto repeat;
}
/*
* Has the page moved or been split?
* Has the page moved?
* This is part of the lockless pagecache protocol. See
* include/linux/pagemap.h for details.
*/
if (unlikely(page != xas_reload(&xas))) {
put_page(page);
put_page(head);
goto repeat;
}
page = find_subpage(page, offset);
out:
rcu_read_unlock();
......@@ -1707,6 +1709,7 @@ unsigned find_get_entries(struct address_space *mapping,
rcu_read_lock();
xas_for_each(&xas, page, ULONG_MAX) {
struct page *head;
if (xas_retry(&xas, page))
continue;
/*
......@@ -1717,13 +1720,17 @@ unsigned find_get_entries(struct address_space *mapping,
if (xa_is_value(page))
goto export;
if (!page_cache_get_speculative(page))
head = compound_head(page);
if (!page_cache_get_speculative(head))
goto retry;
/* Has the page moved or been split? */
/* The page was split under us? */
if (compound_head(page) != head)
goto put_page;
/* Has the page moved? */
if (unlikely(page != xas_reload(&xas)))
goto put_page;
page = find_subpage(page, xas.xa_index);
export:
indices[ret] = xas.xa_index;
......@@ -1732,7 +1739,7 @@ unsigned find_get_entries(struct address_space *mapping,
break;
continue;
put_page:
put_page(page);
put_page(head);
retry:
xas_reset(&xas);
}
......@@ -1774,27 +1781,33 @@ unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start,
rcu_read_lock();
xas_for_each(&xas, page, end) {
struct page *head;
if (xas_retry(&xas, page))
continue;
/* Skip over shadow, swap and DAX entries */
if (xa_is_value(page))
continue;
if (!page_cache_get_speculative(page))
head = compound_head(page);
if (!page_cache_get_speculative(head))
goto retry;
/* Has the page moved or been split? */
/* The page was split under us? */
if (compound_head(page) != head)
goto put_page;
/* Has the page moved? */
if (unlikely(page != xas_reload(&xas)))
goto put_page;
pages[ret] = find_subpage(page, xas.xa_index);
pages[ret] = page;
if (++ret == nr_pages) {
*start = xas.xa_index + 1;
goto out;
}
continue;
put_page:
put_page(page);
put_page(head);
retry:
xas_reset(&xas);
}
......@@ -1839,6 +1852,7 @@ unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
rcu_read_lock();
for (page = xas_load(&xas); page; page = xas_next(&xas)) {
struct page *head;
if (xas_retry(&xas, page))
continue;
/*
......@@ -1848,19 +1862,24 @@ unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
if (xa_is_value(page))
break;
if (!page_cache_get_speculative(page))
head = compound_head(page);
if (!page_cache_get_speculative(head))
goto retry;
/* Has the page moved or been split? */
/* The page was split under us? */
if (compound_head(page) != head)
goto put_page;
/* Has the page moved? */
if (unlikely(page != xas_reload(&xas)))
goto put_page;
pages[ret] = find_subpage(page, xas.xa_index);
pages[ret] = page;
if (++ret == nr_pages)
break;
continue;
put_page:
put_page(page);
put_page(head);
retry:
xas_reset(&xas);
}
......@@ -1896,6 +1915,7 @@ unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,
rcu_read_lock();
xas_for_each_marked(&xas, page, end, tag) {
struct page *head;
if (xas_retry(&xas, page))
continue;
/*
......@@ -1906,21 +1926,26 @@ unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,
if (xa_is_value(page))
continue;
if (!page_cache_get_speculative(page))
head = compound_head(page);
if (!page_cache_get_speculative(head))
goto retry;
/* Has the page moved or been split? */
/* The page was split under us? */
if (compound_head(page) != head)
goto put_page;
/* Has the page moved? */
if (unlikely(page != xas_reload(&xas)))
goto put_page;
pages[ret] = find_subpage(page, xas.xa_index);
pages[ret] = page;
if (++ret == nr_pages) {
*index = xas.xa_index + 1;
goto out;
}
continue;
put_page:
put_page(page);
put_page(head);
retry:
xas_reset(&xas);
}
......@@ -2603,7 +2628,7 @@ void filemap_map_pages(struct vm_fault *vmf,
pgoff_t last_pgoff = start_pgoff;
unsigned long max_idx;
XA_STATE(xas, &mapping->i_pages, start_pgoff);
struct page *page;
struct page *head, *page;
rcu_read_lock();
xas_for_each(&xas, page, end_pgoff) {
......@@ -2612,19 +2637,24 @@ void filemap_map_pages(struct vm_fault *vmf,
if (xa_is_value(page))
goto next;
head = compound_head(page);
/*
* Check for a locked page first, as a speculative
* reference may adversely influence page migration.
*/
if (PageLocked(page))
if (PageLocked(head))
goto next;
if (!page_cache_get_speculative(page))
if (!page_cache_get_speculative(head))
goto next;
/* Has the page moved or been split? */
/* The page was split under us? */
if (compound_head(page) != head)
goto skip;
/* Has the page moved? */
if (unlikely(page != xas_reload(&xas)))
goto skip;
page = find_subpage(page, xas.xa_index);
if (!PageUptodate(page) ||
PageReadahead(page) ||
......
......@@ -2496,9 +2496,6 @@ static void __split_huge_page(struct page *page, struct list_head *list,
if (IS_ENABLED(CONFIG_SHMEM) && PageSwapBacked(head))
shmem_uncharge(head->mapping->host, 1);
put_page(head + i);
} else if (!PageAnon(page)) {
__xa_store(&head->mapping->i_pages, head[i].index,
head + i, 0);
}
}
......
......@@ -1378,7 +1378,7 @@ static void collapse_shmem(struct mm_struct *mm,
result = SCAN_FAIL;
goto xa_locked;
}
xas_store(&xas, new_page);
xas_store(&xas, new_page + (index % HPAGE_PMD_NR));
nr_none++;
continue;
}
......@@ -1454,7 +1454,7 @@ static void collapse_shmem(struct mm_struct *mm,
list_add_tail(&page->lru, &pagelist);
/* Finally, replace with the new page. */
xas_store(&xas, new_page);
xas_store(&xas, new_page + (index % HPAGE_PMD_NR));
continue;
out_unlock:
unlock_page(page);
......
......@@ -39,7 +39,6 @@ static void memfd_tag_pins(struct xa_state *xas)
xas_for_each(xas, page, ULONG_MAX) {
if (xa_is_value(page))
continue;
page = find_subpage(page, xas->xa_index);
if (page_count(page) - page_mapcount(page) > 1)
xas_set_mark(xas, MEMFD_TAG_PINNED);
......@@ -89,7 +88,6 @@ static int memfd_wait_for_pins(struct address_space *mapping)
bool clear = true;
if (xa_is_value(page))
continue;
page = find_subpage(page, xas.xa_index);
if (page_count(page) - page_mapcount(page) != 1) {
/*
* On the last scan, we clean up all those tags
......
......@@ -463,7 +463,7 @@ int migrate_page_move_mapping(struct address_space *mapping,
for (i = 1; i < HPAGE_PMD_NR; i++) {
xas_next(&xas);
xas_store(&xas, newpage);
xas_store(&xas, newpage + i);
}
}
......
......@@ -614,7 +614,7 @@ static int shmem_add_to_page_cache(struct page *page,
if (xas_error(&xas))
goto unlock;
next:
xas_store(&xas, page);
xas_store(&xas, page + i);
if (++i < nr) {
xas_next(&xas);
goto next;
......
......@@ -132,7 +132,7 @@ int add_to_swap_cache(struct page *page, swp_entry_t entry, gfp_t gfp)
for (i = 0; i < nr; i++) {
VM_BUG_ON_PAGE(xas.xa_index != idx + i, page);
set_page_private(page + i, entry.val + i);
xas_store(&xas, page);
xas_store(&xas, page + i);
xas_next(&xas);
}
address_space->nrpages += nr;
......@@ -167,7 +167,7 @@ void __delete_from_swap_cache(struct page *page, swp_entry_t entry)
for (i = 0; i < nr; i++) {
void *entry = xas_store(&xas, NULL);
VM_BUG_ON_PAGE(entry != page, entry);
VM_BUG_ON_PAGE(entry != page + i, entry);
set_page_private(page + i, 0);
xas_next(&xas);
}
......
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