--- /dev/null
+From ccaba785821970f422c47770331c7e3271763f17 Mon Sep 17 00:00:00 2001
+From: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
+Date: Mon, 8 Jun 2026 17:09:39 +0800
+Subject: Revert "f2fs: remove non-uptodate folio from the page cache in move_data_block"
+
+From: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
+
+commit ccaba785821970f422c47770331c7e3271763f17 upstream.
+
+This reverts commit 9609dd704725a40cd63d915f2ab6c44248a44598.
+
+The kernel panics are keeping to be reported especially when the f2fs
+partition get almost full. By investigation, we find that the reason is
+one f2fs page got freed to buddy without being deleted from LRU and the
+root cause is the race happened in [2] which is enrolled by this commit.
+
+There are 3 race processes in this scenario, please find below for their
+main activities.
+
+The changed code in move_data_block() lets the GC path evict the tail-end
+folio from the page cache through folio_end_dropbehind(). Once
+folio_unmap_invalidate() removes the folio from mapping->i_pages, the
+page-cache references for all pages in the folio are dropped. The folio
+is then kept alive only by temporary external references, which allows a
+later split to operate on a folio whose subpages are no longer protected
+by page-cache references.
+
+After the page-cache references are gone, split_folio_to_order() can
+split the big folio into individual pages and put the resulting subpages
+back on the LRU. For tail pages beyond EOF, split removes them from the
+page cache and drops their page-cache references. A tail page can then
+remain on the LRU with PG_lru set while holding only the split caller's
+temporary reference. When free_folio_and_swap_cache() drops that final
+reference, the page enters the final folio_put() release path.
+
+In parallel, folio_isolate_lru() can observe the same tail page with a
+non-zero refcount and PG_lru set. It clears PG_lru before taking its own
+reference. If this races with the final folio_put() from the split path,
+__folio_put() sees PG_lru already cleared and skips lruvec_del_folio().
+The page is then freed back to the allocator while its lru links are
+still present in the LRU list. A later LRU operation on a neighboring
+page detects the stale link and reports list corruption.
+
+[1]
+[ 22.486082] list_del corruption. next->prev should be fffffffec10e0ac8, but was dead000000000122. (next=fffffffec10e0a88)
+[ 22.486130] ------------[ cut here ]------------
+[ 22.486134] kernel BUG at lib/list_debug.c:67!
+[ 22.486141] Internal error: Oops - BUG: 00000000f2000800 [#1] SMP
+[ 22.488502] Tainted: [W]=WARN, [O]=OOT_MODULE
+[ 22.488506] Hardware name: Spreadtrum UMS9230 1H10 SoC (DT)
+[ 22.488511] pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
+[ 22.488517] pc : __list_del_entry_valid_or_report+0x14c/0x154
+[ 22.488531] lr : __list_del_entry_valid_or_report+0x14c/0x154
+[ 22.488539] sp : ffffffc08006b830
+[ 22.488542] x29: ffffffc08006b868 x28: 0000000000003020 x27: 0000000000000000
+[ 22.488553] x26: 0000000000000000 x25: 0000000000000004 x24: fffffffec10e0ac0
+[ 22.488564] x23: 00000000000000e8 x22: 0000000000000024 x21: dead000000000122
+[ 22.488574] x20: fffffffec10e0a88 x19: fffffffec10e0ac8 x18: ffffffc080061060
+[ 22.488585] x17: 20747562202c3863 x16: 6130653031636566 x15: 0000000000000058
+[ 22.488595] x14: 0000000000000004 x13: ffffff80f91e0000 x12: 0000000000000003
+[ 22.488605] x11: 0000000000000003 x10: 0000000000000001 x9 : ffe85721f0e25f00
+[ 22.488615] x8 : ffe85721f0e25f00 x7 : 0000000000000000 x6 : 6c65645f7473696c
+[ 22.488625] x5 : ffffffed39b23026 x4 : 0000000000000000 x3 : 0000000000000010
+[ 22.488636] x2 : 0000000000000000 x1 : 0000000000000000 x0 : 000000000000006d
+[ 22.488647] Call trace:
+[ 22.488651] __list_del_entry_valid_or_report+0x14c/0x154 (P)
+[ 22.488661] __folio_put+0x2bc/0x434
+[ 22.488670] folio_put+0x28/0x58
+[ 22.488678] do_garbage_collect+0x1a34/0x2584
+[ 22.488689] f2fs_gc+0x230/0x9b4
+[ 22.488697] f2fs_fallocate+0xb90/0xdf4
+[ 22.488706] vfs_fallocate+0x1b4/0x2bc
+[ 22.488716] __arm64_sys_fallocate+0x44/0x78
+[ 22.488725] invoke_syscall+0x58/0xe4
+[ 22.488732] do_el0_svc+0x48/0xdc
+[ 22.488739] el0_svc+0x3c/0x98
+[ 22.488747] el0t_64_sync_handler+0x20/0x130
+[ 22.488754] el0t_64_sync+0x1c4/0x1c8
+
+[2]
+CPU0 (f2fs GC) CPU1 (split_folio_to_order) CPU2 (folio_isolate_lru)
+
+F: pagecache refs = n
+F: extra refs = GC + split
+F: PG_lru set
+move_data_block()
+folio = f2fs_grab_cache_folio(F)
+...
+__folio_set_dropbehind(F)
+folio_unlock(F)
+folio_end_dropbehind(F)
+ folio_unmap_invalidate(F)
+ __filemap_remove_folio(F)
+ folio_put_refs(F, n)
+folio_put(F)
+ split_folio_to_order(F)
+ folio_ref_freeze(F, 1)
+ ...
+ lru_add_split_folio(T)
+ list_add_tail(&T->lru, &F->lru)
+ folio_set_lru(T)
+ __filemap_remove_folio(T)
+ folio_put_refs(T, 1)
+ /* T refcount == 1, PageLRU set */
+ folio_isolate_lru(T)
+ folio_test_clear_lru(T)
+ free_folio_and_swap_cache(T)
+ folio_put(T)
+ /* refcount: 1 -> 0 */
+ __folio_put(T)
+ __page_cache_release(T)
+ folio_test_lru(T) == false
+ /* skip lruvec_del_folio(T) */
+ free_frozen_pages(T)
+ folio_get(T)
+ lruvec_del_folio(T)
+later:
+ list_del(adjacent->lru)
+ next == &T->lru
+ next->prev == LIST_POISON / PCP freelist
+ BUG
+
+Cc: stable@vger.kernel.org
+Fixes: 9609dd704725 ("f2fs: remove non-uptodate folio from the page cache in move_data_block")
+Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
+Reviewed-by: Chao Yu <chao@kernel.org>
+Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ fs/f2fs/gc.c | 6 +-----
+ 1 file changed, 1 insertion(+), 5 deletions(-)
+
+--- a/fs/f2fs/gc.c
++++ b/fs/f2fs/gc.c
+@@ -1487,11 +1487,7 @@ up_out:
+ put_out:
+ f2fs_put_dnode(&dn);
+ out:
+- if (!folio_test_uptodate(folio))
+- __folio_set_dropbehind(folio);
+- folio_unlock(folio);
+- folio_end_dropbehind(folio);
+- folio_put(folio);
++ f2fs_folio_put(folio, true);
+ out_iput:
+ if (atomic_inode)
+ iput(atomic_inode);
projects / thirdparty / kernel / stable-queue.git / commitdiff
