linux-kernel - Re: [mm/vmalloc] 5c1f4e690e: BUG:sleeping_function_called_from_invalid_context_at_mm/page

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Message-ID: <CAHk-=wiDif7SvA5DOWj9ssDuYHC4ujUFPd7ad-ydhY-WMLb-kQ@mail.gmail.com>
Date:   Tue, 13 Jul 2021 11:19:29 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     kernel test robot <oliver.sang@...el.com>,
        Uladzislau Rezki <urezki@...il.com>,
        Mel Gorman <mgorman@...e.de>
Cc:     Hillf Danton <hdanton@...a.com>,
        Matthew Wilcox <willy@...radead.org>,
        Michal Hocko <mhocko@...e.com>,
        Nicholas Piggin <npiggin@...il.com>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...ymobile.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>, lkp@...ts.01.org,
        kernel test robot <lkp@...el.com>
Subject: Re: [mm/vmalloc] 5c1f4e690e: BUG:sleeping_function_called_from_invalid_context_at_mm/page_alloc.c

On Tue, Jul 13, 2021 at 7:06 AM kernel test robot <oliver.sang@...el.com> wrote:
>
> [  131.014885] BUG: sleeping function called from invalid context at mm/page_alloc.c:4992

Strange. The call chain doesn't actually seem to be anything off: it's
writev -> sock_write_iter -> sock_sendmsg -> netlink_sendmsg ->
vmalloc.

All good to sleep as far as I can tell. The warning itself seems to be just

        might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);

in prepare_alloc_pages().

I don't see what's wrong with that commit, but it does seem to be very
consistent, in that the parent doesn't have it:

 > +----------------------------------------------------------------------+------------+------------+
> |                                                                      | a2afc59fb2 | 5c1f4e690e |
> +----------------------------------------------------------------------+------------+------------+
> | BUG:sleeping_function_called_from_invalid_context_at_mm/page_alloc.c | 0          | 54         |
> +----------------------------------------------------------------------+------------+------------+

Does anybody see what the problem is there?

There's an odd report _after_ the warning:

[  131.345319] raw_local_irq_restore() called with IRQs enabled
[  131.366561] RIP: 0010:warn_bogus_irq_restore+0x1d/0x20
[  131.433334]  __alloc_pages_bulk+0xbb8/0xf20

but I think that's might be a result of the BUG(). Maybe. But it might
also be indicative of some context confusion - do we end up nesting?
Because the BUG() has

[  131.036625] hardirqs last disabled at (283042):
[<ffffffff81656d71>] __alloc_pages_bulk+0xae1/0xf20

which means that the might_sleep_if() happens _after_
__alloc_pages_bulk() has disabled interrupts. That would explain it,
but the stack_depot_save() thing actually makes that call chain really
hard to read because it duplicates the addresses on the stack.

I don't see the nesting there, but that's what it kind of smells like to me.

Anybody?

               Linus