d2acf78908
| 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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.