On Wed 31-08-16 16:04:57, James Morse wrote: > Trying to walk all of virtual memory requires architecture specific > knowledge. On x86_64, addresses must be sign extended from bit 48, > whereas on arm64 the top VA_BITS of address space have their own set > of page tables. > > mem_cgroup_count_precharge() and mem_cgroup_move_charge() both call > walk_page_range() on the range 0 to ~0UL, neither provide a pte_hole > callback, which causes the current implementation to skip non-vma regions. > > As this call only expects to walk user address space, make it walk > 0 to 'highest_vm_end'. > > Signed-off-by: James Morse <james.morse@xxxxxxx> > Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> > --- > This is in preparation for a RFC series that allows walk_page_range() to > walk kernel page tables too. OK, so do I get it right that this is only needed with that change? Because AFAICS walk_page_range will be bound to the last vma->vm_end right now. If this is the case this should be mentioned in the changelog because the above might confuse somebody to think this is a bug fix. Other than that this seams reasonable to me. > > mm/memcontrol.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 2ff0289ad061..bfd54b43beb9 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -4712,7 +4712,8 @@ static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm) > .mm = mm, > }; > down_read(&mm->mmap_sem); > - walk_page_range(0, ~0UL, &mem_cgroup_count_precharge_walk); > + walk_page_range(0, mm->highest_vm_end, > + &mem_cgroup_count_precharge_walk); > up_read(&mm->mmap_sem); > > precharge = mc.precharge; > @@ -5000,7 +5001,8 @@ retry: > * When we have consumed all precharges and failed in doing > * additional charge, the page walk just aborts. > */ > - walk_page_range(0, ~0UL, &mem_cgroup_move_charge_walk); > + walk_page_range(0, mc.mm->highest_vm_end, &mem_cgroup_move_charge_walk); > + > up_read(&mc.mm->mmap_sem); > atomic_dec(&mc.from->moving_account); > } > -- > 2.8.0.rc3 > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@xxxxxxxxx. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
