linux-kernel - Re: [PATCH v3 31/35] lib: add memory allocations report in show

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Message-ID: <CAJuCfpHc2ee_V6SGAc_31O_ikjGGNivhdSG+2XNcc9vVmzO-9g@mail.gmail.com>
Date: Thu, 15 Feb 2024 06:58:42 -0800
From: Suren Baghdasaryan <surenb@...gle.com>
To: Michal Hocko <mhocko@...e.com>
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Subject: Re: [PATCH v3 31/35] lib: add memory allocations report in show_mem()

On Thu, Feb 15, 2024 at 1:22 AM Michal Hocko <mhocko@...e.com> wrote:
>
> On Mon 12-02-24 13:39:17, Suren Baghdasaryan wrote:
> [...]
> > @@ -423,4 +424,18 @@ void __show_mem(unsigned int filter, nodemask_t *nodemask, int max_zone_idx)
> >  #ifdef CONFIG_MEMORY_FAILURE
> >       printk("%lu pages hwpoisoned\n", atomic_long_read(&num_poisoned_pages));
> >  #endif
> > +#ifdef CONFIG_MEM_ALLOC_PROFILING
> > +     {
> > +             struct seq_buf s;
> > +             char *buf = kmalloc(4096, GFP_ATOMIC);
> > +
> > +             if (buf) {
> > +                     printk("Memory allocations:\n");
> > +                     seq_buf_init(&s, buf, 4096);
> > +                     alloc_tags_show_mem_report(&s);
> > +                     printk("%s", buf);
> > +                     kfree(buf);
> > +             }
> > +     }
> > +#endif
>
> I am pretty sure I have already objected to this. Memory allocations in
> the oom path are simply no go unless there is absolutely no other way
> around that. In this case the buffer could be preallocated.

Good point. We will change this to a smaller buffer allocated on the
stack and will print records one-by-one. Thanks!

>
> --
> Michal Hocko
> SUSE Labs