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

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Message-ID: <CAJuCfpE2hMx4rUSex3rX_wWiGOt=rX5FWms98Rd6WAaVqW6yvw@mail.gmail.com>
Date: Tue, 13 Feb 2024 00:17:04 -0800
From: Suren Baghdasaryan <surenb@...gle.com>
To: Kent Overstreet <kent.overstreet@...ux.dev>
Cc: Steven Rostedt <rostedt@...dmis.org>, Kees Cook <keescook@...omium.org>, 
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Subject: Re: [PATCH v3 31/35] lib: add memory allocations report in show_mem()

On Mon, Feb 12, 2024 at 8:33 PM Kent Overstreet
<kent.overstreet@...ux.dev> wrote:
>
> On Mon, Feb 12, 2024 at 07:22:42PM -0500, Steven Rostedt wrote:
> > On Mon, 12 Feb 2024 16:10:02 -0800
> > Kees Cook <keescook@...omium.org> wrote:
> >
> > > >  #endif
> > > > +#ifdef CONFIG_MEM_ALLOC_PROFILING
> > > > + {
> > > > +         struct seq_buf s;
> > > > +         char *buf = kmalloc(4096, GFP_ATOMIC);
> > >
> > > Why 4096? Maybe use PAGE_SIZE instead?
> >
> > Will it make a difference for architectures that don't have 4096 PAGE_SIZE?
> > Like PowerPC which has PAGE_SIZE of anywhere between 4K to 256K!
>
> it's just a string buffer

We should document that __show_mem() prints only the top 10 largest
allocations, therefore as long as this buffer is large enough to hold
10 records we should be good. Technically we could simply print one
record at a time and then the buffer can be smaller.