Re: [PATCH] mm: add warning if __vm_enough_memory fails

[Kefeng Wang]

On 2022/7/26 21:45, David Hildenbrand wrote:
> On 26.07.22 09:24, Kefeng Wang wrote:
> > If a process has no enough memory to allocate a new virtual mapping, we
> > may meet kinds of error, eg, fork cannot allocate memory, SIGBUS error
> > in shmem, but it is difficult to confirm them, let's add some debug
> > information to easy to check this scenario if __vm_enough_memory fails.
> >
> > Reported-by: Yongqiang Liu <liuyongqiang13@xxxxxxxxxx>
> > Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
> > ---
> >   mm/util.c | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/mm/util.c b/mm/util.c
> > index 1266a33a49ea..19bfff8a0ad6 100644
> > --- a/mm/util.c
> > +++ b/mm/util.c
> > @@ -1020,6 +1020,8 @@ int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
> >   	if (percpu_counter_read_positive(&vm_committed_as) < allowed)
> >   		return 0;
> >   error:
> > +	pr_warn("%s: pid: %d, comm: %s, no enough memory for the allocation\n",
> > +		__func__, current->pid, current->comm);
> >   	vm_unacct_memory(pages);
> >   
> >   	return -ENOMEM;
> Users can easily spam the kernel log, no? Maybe at least ratelimit.
pr_warn_ratelimited is better, will update, thanks.
>