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From: Eric Sandeen <sandeen@sandeen.net>
To: Blake Golliher <bgolliher@box.com>
Cc: Chris Holcombe <cholcombe@box.com>,
	"Darrick J. Wong" <darrick.wong@oracle.com>,
	linux-xfs@vger.kernel.org
Subject: Re: XFS: possible memory allocation deadlock in kmem_alloc
Date: Tue, 5 Nov 2019 14:47:50 -0600	[thread overview]
Message-ID: <33b9bde4-fd14-8754-f98a-ae0f363e76be@sandeen.net> (raw)
In-Reply-To: <CAC752AnZ4biDGk6V17URQm5YVp=MwZBhiMH8=t733zaypxUsmA@mail.gmail.com>

On 11/5/19 2:36 PM, Blake Golliher wrote:
> We don't get anything more then this messages.
> 
> [Tue Nov  5 11:18:34 2019] XFS: nginx(2540) possible memory allocation deadlock size 63960 in kmem_alloc (mode:0x250)
> 
> [Tue Nov  5 11:18:34 2019] XFS: nginx(2517) possible memory allocation deadlock size 56880 in kmem_alloc (mode:0x250)
> 
> [Tue Nov  5 11:18:34 2019] XFS: nginx(2540) possible memory allocation deadlock size 63960 in kmem_alloc (mode:0x250)
> 
> [Tue Nov  5 11:18:35 2019] XFS: nginx(2517) possible memory allocation deadlock size 56880 in kmem_alloc (mode:0x250)
> 
> [Tue Nov  5 11:18:36 2019] XFS: nginx(2514) possible memory allocation deadlock size 63960 in kmem_alloc (mode:0x250)
> 
> [Tue Nov  5 11:18:36 2019] XFS: nginx(2540) possible memory allocation deadlock size 63960 in kmem_alloc (mode:0x250)
> 
> [Tue Nov  5 11:18:37 2019] XFS: nginx(2517) possible memory allocation deadlock size 56880 in kmem_alloc (mode:0x250)

no sure what to say.  In that kernel, when we print the message:

                        xfs_err(NULL,
        "%s(%u) possible memory allocation deadlock size %u in %s (mode:0x%x)",
                                current->comm, current->pid,
                                (unsigned int)size, __func__, lflags);

xfs_err() is:

define_xfs_printk_level(xfs_err, KERN_ERR);

which is the macro:

#define define_xfs_printk_level(func, kern_level)               \
void func(const struct xfs_mount *mp, const char *fmt, ...)     \
{                                                               \
        struct va_format        vaf;                            \
        va_list                 args;                           \
        int                     level;                          \
                                                                \
        va_start(args, fmt);                                    \
                                                                \
        vaf.fmt = fmt;                                          \
        vaf.va = &args;                                         \
                                                                \
        __xfs_printk(kern_level, mp, &vaf);                     \
        va_end(args);                                           \
                                                                \
        if (!kstrtoint(kern_level, 0, &level) &&                \ 
            level <= 3 /* LOGLEVEL_ERR */ &&                    \
            xfs_error_level >= XFS_ERRLEVEL_HIGH)               \
                xfs_stack_trace();                              \
}                                                               \

which should dump a stack if called w/ ERR priority and the xfs_error_level is at 11.

I suppose your general kernel ring buffer needs to be turned up high enough
as well (i.e. dmesg -n 8 to be sure?)

The resulting stack trace would tell us exactly how you got to the 
allocation message.

-Eric

  parent reply	other threads:[~2019-11-05 20:47 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-04 23:38 XFS: possible memory allocation deadlock in kmem_alloc Chris Holcombe
2019-11-05  0:01 ` Darrick J. Wong
2019-11-05  0:31   ` Eric Sandeen
     [not found]     ` <CAC752AmahECFry9x=pvqDkwQUj1PEJjoWGa2KFG1uaTzT1Bbnw@mail.gmail.com>
2019-11-05  4:21       ` Eric Sandeen
2019-11-05 16:25         ` Chris Holcombe
2019-11-05 17:11           ` Eric Sandeen
2019-11-05 19:53             ` Chris Holcombe
2019-11-05 20:08               ` Eric Sandeen
     [not found]                 ` <CAC752AnZ4biDGk6V17URQm5YVp=MwZBhiMH8=t733zaypxUsmA@mail.gmail.com>
2019-11-05 20:47                   ` Eric Sandeen [this message]
     [not found]                     ` <CAC752A=y9PMEQ1e4mXskha1GFeKXWi8PsdBW-nX40pgFCYp1Uw@mail.gmail.com>
2019-11-05 21:23                       ` Eric Sandeen
  -- strict thread matches above, loose matches on Subject: below --
2016-05-30  4:45 baotiao
2016-05-30  5:04 ` Dave Chinner
2016-05-30  8:48   ` baotiao
2016-05-30  9:20     ` Carlos Maiolino
2016-05-31  2:43     ` 陈宗志
2016-05-31  3:10       ` Dave Chinner
2016-05-31 11:00         ` 陈宗志
2016-05-31 12:14           ` Carlos Maiolino

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