On Tue 13-02-18 12:19:18, Anshuman Khandual wrote:
> On 02/01/2018 07:18 PM, Michal Hocko wrote:
> > On Thu 01-02-18 08:43:34, Anshuman Khandual wrote:
> > [...]
> >> $dmesg | grep elf_brk
> >> [    9.571192] elf_brk 10030328 elf_bss 10030000
> >>
> >> static int load_elf_binary(struct linux_binprm *bprm)
> >> ---------------------
> >>
> >>    if (unlikely (elf_brk > elf_bss)) {
> >>                    unsigned long nbyte;
> >>                
> >>                    /* There was a PT_LOAD segment with p_memsz > p_filesz
> >>                       before this one. Map anonymous pages, if needed,
> >>                       and clear the area.  */
> >>                    retval = set_brk(elf_bss + load_bias,
> >>                                     elf_brk + load_bias,
> >>                                     bss_prot);
> >>
> >>
> >> ---------------------
> > 
> > Just a blind shot... Does the following make any difference?
> > ---
> > diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
> > index 021fe78998ea..04b24d00c911 100644
> > --- a/fs/binfmt_elf.c
> > +++ b/fs/binfmt_elf.c
> > @@ -895,7 +895,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
> >        the correct location in memory. */
> >     for(i = 0, elf_ppnt = elf_phdata;
> >         i < loc->elf_ex.e_phnum; i++, elf_ppnt++) {
> > -           int elf_prot = 0, elf_flags;
> > +           int elf_prot = 0, elf_flags, elf_fixed = MAP_FIXED_NOREPLACE;
> >             unsigned long k, vaddr;
> >             unsigned long total_size = 0;
> >  
> > @@ -927,6 +927,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
> >                                      */
> >                             }
> >                     }
> > +                   elf_fixed = MAP_FIXED;
> >             }
> >  
> >             if (elf_ppnt->p_flags & PF_R)
> > @@ -944,7 +945,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
> >              * the ET_DYN load_addr calculations, proceed normally.
> >              */
> >             if (loc->elf_ex.e_type == ET_EXEC || load_addr_set) {
> > -                   elf_flags |= MAP_FIXED_NOREPLACE;
> > +                   elf_flags |= elf_fixed;
> >             } else if (loc->elf_ex.e_type == ET_DYN) {
> >                     /*
> >                      * This logic is run once for the first LOAD Program
> > @@ -980,7 +981,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
> >                             load_bias = ELF_ET_DYN_BASE;
> >                             if (current->flags & PF_RANDOMIZE)
> >                                     load_bias += arch_mmap_rnd();
> > -                           elf_flags |= MAP_FIXED_NOREPLACE;
> > +                           elf_flags |= elf_fixed;
> >                     } else
> >                             load_bias = 0;
> >  
> > 
> 
> Yeah, it does solve the problem on mmotm-2018-01-25-16-20.

Thanks a lot for testing! I will post an RFC patch shortly.

-- 
Michal Hocko
SUSE Labs

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