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authorPavel Begunkov <asml.silence@gmail.com>2023-03-16 18:26:05 +0300
committerJens Axboe <axboe@kernel.dk>2023-03-16 18:32:18 +0300
commitd2acf789088bb562cea342b6a24e646df4d47839 (patch)
tree2547e9306e1a77859ba816c9f81b96b5d71c2f5e /io_uring/rsrc.c
parent5da28edd7bd5518f97175ecea77615bb729a7a28 (diff)
downloadlinux-d2acf789088bb562cea342b6a24e646df4d47839.tar.xz
io_uring/rsrc: fix folio accounting
| BUG: Bad page state in process kworker/u8:0 pfn:5c001 | page:00000000bfda61c8 refcount:0 mapcount:0 mapping:0000000000000000 index:0x20001 pfn:0x5c001 | head:0000000011409842 order:9 entire_mapcount:0 nr_pages_mapped:0 pincount:1 | anon flags: 0x3fffc00000b0004(uptodate|head|mappedtodisk|swapbacked|node=0|zone=0|lastcpupid=0xffff) | raw: 03fffc0000000000 fffffc0000700001 ffffffff00700903 0000000100000000 | raw: 0000000000000200 0000000000000000 00000000ffffffff 0000000000000000 | head: 03fffc00000b0004 dead000000000100 dead000000000122 ffff00000a809dc1 | head: 0000000000020000 0000000000000000 00000000ffffffff 0000000000000000 | page dumped because: nonzero pincount | CPU: 3 PID: 9 Comm: kworker/u8:0 Not tainted 6.3.0-rc2-00001-gc6811bf0cd87 #1 | Hardware name: linux,dummy-virt (DT) | Workqueue: events_unbound io_ring_exit_work | Call trace: | dump_backtrace+0x13c/0x208 | show_stack+0x34/0x58 | dump_stack_lvl+0x150/0x1a8 | dump_stack+0x20/0x30 | bad_page+0xec/0x238 | free_tail_pages_check+0x280/0x350 | free_pcp_prepare+0x60c/0x830 | free_unref_page+0x50/0x498 | free_compound_page+0xcc/0x100 | free_transhuge_page+0x1f0/0x2b8 | destroy_large_folio+0x80/0xc8 | __folio_put+0xc4/0xf8 | gup_put_folio+0xd0/0x250 | unpin_user_page+0xcc/0x128 | io_buffer_unmap+0xec/0x2c0 | __io_sqe_buffers_unregister+0xa4/0x1e0 | io_ring_exit_work+0x68c/0x1188 | process_one_work+0x91c/0x1a58 | worker_thread+0x48c/0xe30 | kthread+0x278/0x2f0 | ret_from_fork+0x10/0x20 Mark reports an issue with the recent patches coalescing compound pages while registering them in io_uring. The reason is that we try to drop excessive references with folio_put_refs(), but pages were acquired with pin_user_pages(), which has extra accounting and so should be put down with matching unpin_user_pages() or at least gup_put_folio(). As a fix unpin_user_pages() all but first page instead, and let's figure out a better API after. Fixes: 57bebf807e2abcf8 ("io_uring/rsrc: optimise registered huge pages") Reported-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Jens Axboe <axboe@kernel.dk> Tested-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/10efd5507d6d1f05ea0f3c601830e08767e189bd.1678980230.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'io_uring/rsrc.c')
-rw-r--r--io_uring/rsrc.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index 09a16d709cb5..e2bac9f89902 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -1235,7 +1235,13 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, struct iovec *iov,
}
}
if (folio) {
- folio_put_refs(folio, nr_pages - 1);
+ /*
+ * The pages are bound to the folio, it doesn't
+ * actually unpin them but drops all but one reference,
+ * which is usually put down by io_buffer_unmap().
+ * Note, needs a better helper.
+ */
+ unpin_user_pages(&pages[1], nr_pages - 1);
nr_pages = 1;
}
}