Re: [LKP] [mm] Find a way to test remap_file_pages

[Kirill A. Shutemov]

On Mon, Jan 12, 2015 at 02:26:29PM +1100, Stephen Rothwell wrote:
> [Just cc'ing Andrew as this patch is in his tree]
> 
> On Mon, 12 Jan 2015 11:19:01 +0800 Huang Ying <ying.huang@xxxxxxxxx> wrote:
> >
> > FYI, we noticed the below changes on
> > 
> > git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> > commit 974bb1d5d44f008d7f207437d63d46658ff41dff ("mm: replace remap_file_pages() syscall with emulation")
> > 
> > That is, trinity can be used to test some aspect of remap_file_pages.
> > 
> > +---------------------------------------------------+------------+------------+
> > |                                                   | d96eeaf2cb | 974bb1d5d4 |
> > +---------------------------------------------------+------------+------------+
> > | boot_successes                                    | 0          | 0          |
> > | boot_failures                                     | 10         | 10         |
> > | WARNING:at_net/netlink/genetlink.c:#genl_unbind() | 10         | 5          |
> > | backtrace:netlink_setsockopt                      | 3          | 2          |
> > | backtrace:SyS_setsockopt                          | 3          | 2          |
> > | backtrace:SyS_socketcall                          | 3          | 2          |
> > | backtrace:do_group_exit                           | 10         | 5          |
> > | backtrace:SyS_exit_group                          | 10         | 5          |
> > | page_allocation_failure:order:#,mode              | 0          | 5          |
> > | backtrace:btrfs_test_extent_io                    | 0          | 5          |
> > | backtrace:init_btrfs_fs                           | 0          | 5          |
> > | backtrace:kernel_init_freeable                    | 0          | 5          |
> > +---------------------------------------------------+------------+------------+
> > 
> > 
> > [   29.665081] Bits 55-60 of /proc/PID/pagemap entries are about to stop being page-shift some time soon. See the linux/Documentation/vm/pagemap.txt for details.
> > [   29.675960] mmap: trinity-c0 (873) uses deprecated remap_file_pages() syscall. See Documentation/vm/remap_file_pages.txt.
> > [   29.681044] ------------[ cut here ]------------
> > [   29.681841] WARNING: CPU: 0 PID: 870 at net/netlink/genetlink.c:1037 genl_unbind+0x96/0xaa()
> > [   29.683610] warning: process `trinity-c0' used the obsolete bdflush system call
> > [   29.684911] Fix your initscripts?
> > [   29.685683] VFS: Warning: trinity-c0 using old stat() call. Recompile your binary.
> > [   29.686963] CPU: 0 PID: 870 Comm: trinity-main Not tainted 3.19.0-rc3-next-20150109-g06f367d #290
> > [   29.688399] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> > [   29.689349]  00000000 00000000 d34f3ea4
> > [   29.694083] ------------[ cut here ]------------
> > [   29.695096] WARNING: CPU: 0 PID: 872 at net/netlink/genetlink.c:1037 genl_unbind+0x96/0xaa()
> > [   29.696724]  c15933f7 d34f3ec0 c103c7ff 0000040d c1581310
> > [   29.698051]  00000001 00000001 00000000 d34f3ed0 c103c89c 00000009 00000000 d34f3ee8
> > [   29.699904] CPU: 0 PID: 872 Comm: trinity-main Not tainted 3.19.0-rc3-next-20150109-g06f367d #290
> > [   29.701406] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> > [   29.702291]  00000000 00000000 d34d9ea4 c15933f7 d34d9ec0
> > [   29.703253]  c1581310 c18836fc 00000001 d341f840 00000000 d34f3f0c c157f810 d15b0b40
> > [   29.705361] Call Trace:
> > [   29.705868]  [<c15933f7>] dump_stack+0x16/0x18
> > [   29.706652]  [<c103c7ff>] warn_slowpath_common+0x79/0x90
> > [   29.707496]  [<c1581310>] ? genl_unbind+0x96/0xaa
> > [   29.708295]  [<c103c89c>] warn_slowpath_null+0xf/0x13
> > [   29.709142]  [<c1581310>] genl_unbind+0x96/0xaa
> > [   29.709943]  [<c157f810>] netlink_release+0x2d7/0x2ed
> > [   29.710776]  [<c1553efd>] sock_release+0x10/0x5a
> > [   29.711531]  [<c1553f52>] sock_close+0xb/0xf
> > [   29.712286]  [<c1109a69>] __fput+0xf7/0x1f0
> > [   29.713044]  [<c1109b88>] ____fput+0x8/0xa
> > [   29.713794]  [<c1052412>] task_work_run+0x4e/0x70
> > [   29.714566]  [<c103e771>] do_exit+0x43a/0x9c7
> > [   29.715300]  [<c103ed6f>] do_group_exit+0x4a/0xd6
> > [   29.716111]  [<c103ee0c>] SyS_exit_group+0x11/0x11
> > [   29.716975]  [<c1598cfd>] syscall_call+0x7/0x7
> > [   29.717722]  [<c1590000>] ? io_submit_one+0x5b3/0x72a
> > [   29.719207]  c103c7ff 0000040d c1581310
> > [   29.720122]  00000001 00000001 00000000 d34d9ed0 c103c89c 00000009 00000000 d34d9ee8
> > [   29.721973]  c1581310 c18836fc 00000004 d0ebb840 00000000 d34d9f0c c157f810
> > [   29.723252] ---[ end trace 28426633f87b780a ]---
> > [   29.724282] ------------[ cut here ]------------


It doesn't make much sense to me. I don't see anything
remap_file_pages()-related here. Or even VMA related.

And why now? The commit is in Andrew's tree for few release cycles.

Could you elaborate on what you observe? And what the table above means?

-- 
 Kirill A. Shutemov
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