On Tue, Mar 10, 2020 at 07:58:46PM -0400, Qian Cai wrote:
The commit bd4c82c22c36 ("mm, THP, swap: delay splitting THP after swapped out") supported writing THP to a swap device but forgot to upgrade an older commit df8c94d13c7e ("page-flags: define behavior of FS/IO-related flags on compound pages") which could trigger a crash during THP swapping out with DEBUG_VM_PGFLAGS=y,
kernel BUG at include/linux/page-flags.h:317!
page dumped because: VM_BUG_ON_PAGE(1 && PageCompound(page)) page:fffff3b2ec3a8000 refcount:512 mapcount:0 mapping:000000009eb0338c index:0x7f6e58200 head:fffff3b2ec3a8000 order:9 compound_mapcount:0 compound_pincount:0 anon flags: 0x45fffe0000d8454(uptodate|lru|workingset|owner_priv_1|writeback|head|reclaim|swapbacked)
end_swap_bio_write() SetPageError(page) VM_BUG_ON_PAGE(1 && PageCompound(page))
<IRQ> bio_endio+0x297/0x560 dec_pending+0x218/0x430 [dm_mod] clone_endio+0xe4/0x2c0 [dm_mod] bio_endio+0x297/0x560 blk_update_request+0x201/0x920 scsi_end_request+0x6b/0x4b0 scsi_io_completion+0x509/0x7e0 scsi_finish_command+0x1ed/0x2a0 scsi_softirq_done+0x1c9/0x1d0 __blk_mqnterrupt+0xf/0x20 </IRQ>
Fix by checking PF_NO_TAIL in those places instead.
Fixes: bd4c82c22c36 ("mm, THP, swap: delay splitting THP after swapped out") Cc: stable@vger.kernel.org Signed-off-by: Qian Cai cai@lca.pw
include/linux/page-flags.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 1bf83c8fcaa7..77de28bfefb0 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -311,7 +311,7 @@ static inline int TestClearPage##uname(struct page *page) { return 0; } __PAGEFLAG(Locked, locked, PF_NO_TAIL) PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) __CLEARPAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) -PAGEFLAG(Error, error, PF_NO_COMPOUND) TESTCLEARFLAG(Error, error, PF_NO_COMPOUND) +PAGEFLAG(Error, error, PF_NO_TAIL) TESTCLEARFLAG(Error, error, PF_NO_TAIL) PAGEFLAG(Referenced, referenced, PF_HEAD) TESTCLEARFLAG(Referenced, referenced, PF_HEAD) __SETPAGEFLAG(Referenced, referenced, PF_HEAD) -- 2.21.0 (Apple Git-122.2)
Acked-by: Rafael Aquini aquini@redhat.com