Re: [PATCH] mm/page_owner: print largest memory consumer when OOM panic occurs

[Qian Cai <cai@lca.pw>]

> On Dec 24, 2019, at 1:45 AM, Miles Chen <miles.chen@mediatek.com> wrote:
> 
> We use kmemleak too, but a memory leakage which is caused by
> alloc_pages() in a kernel device driver cannot be caught by kmemleak.
> We have fought against this kind of real problems for a few years and 
> find a way to make the debugging easier.
> 
> We currently have information during OOM: process Node, zone, swap, 
> process (pid, rss, name), slab usage, and the backtrace, order, and
> gfp flags of the OOM backtrace. 
> We can tell many different types of OOM problems by the information
> above except the alloc_pages() leakage.
> 
> The patch does work and save a lot of debugging time.
> Could we consider the "greatest memory consumer" as another useful 
> OOM information?

This is rather situational considering there are memory leaks here and there but it is not necessary that straightforward as a single place of greatest consumer.

The other question is why the offensive drivers that use alloc_pages() repeatedly without using any object allocator? Do you have examples of this in drivers that could happen?