On Thu, 16 Jul 2020 at 12:07, Naresh Kamboju <naresh.kamboju@xxxxxxxxxx> wrote: > > On Thu, 16 Jul 2020 at 04:49, Linus Torvalds > <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > > > On Wed, Jul 15, 2020 at 4:04 PM Linus Torvalds > > <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > > > > > It *might* be as simple as this incremental thing on top > > > > No, it needs to be > > > > + if (*old_addr + *len < old->vm_end) > > + return; > > > > in try_to_align_end(), of course. > > > > Now I'm going for a lie-down, because this cross-eyed thing isn't working. > > > Just want to double check. > Here is the diff after those two patches applied. Please correct me if > it is wrong. > This patch applied on top of Linus mainline master branch. > I am starting my test cycles. Sorry this patch (the below pasted ) did not solve the reported problem. I still notice warning [ 760.004318] ------------[ cut here ]------------ [ 760.009039] WARNING: CPU: 3 PID: 461 at mm/mremap.c:230 move_page_tables+0x818/0x840 [ 760.016848] Modules linked in: x86_pkg_temp_thermal fuse [ 760.022220] CPU: 3 PID: 461 Comm: true Not tainted 5.8.0-rc5 #1 [ 760.028198] Hardware name: Supermicro SYS-5019S-ML/X11SSH-F, BIOS 2.2 05/23/2018 [ 760.035651] EIP: move_page_tables+0x818/0x840 ref: https://lkft.validation.linaro.org/scheduler/job/1574277#L12221 > > --- > mm/mremap.c | 73 +++++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 73 insertions(+) > > diff --git a/mm/mremap.c b/mm/mremap.c > index 6b153dc05fe4..4961c18d2008 100644 > --- a/mm/mremap.c > +++ b/mm/mremap.c > @@ -254,6 +254,77 @@ static bool move_normal_pmd(struct vm_area_struct > *vma, unsigned long old_addr, > > return true; > } > + > +#define ADDR_BEFORE_PREV(addr, vma) \ > + ((vma)->vm_prev && (addr) < (vma)->vm_prev->vm_end) > + > +static inline void try_to_align_start(unsigned long *len, > + struct vm_area_struct *old, unsigned long *old_addr, > + struct vm_area_struct *new, unsigned long *new_addr) > +{ > + if (*old_addr > old->vm_start) > + return; > + > + if (ADDR_BEFORE_PREV(*old_addr & PMD_MASK, old)) > + return; > + > + if (ADDR_BEFORE_PREV(*new_addr & PMD_MASK, new)) > + return; > + > + /* Bingo! */ > + *len += *new_addr & ~PMD_MASK; > + *old_addr &= PMD_MASK; > + *new_addr &= PMD_MASK; > +} > + > +/* > + * When aligning the end, avoid ALIGN() (which can overflow > + * if the user space is the full address space, and overshoot > + * the vm_start of the next vma). > + * > + * Align the upper limit down instead, and check that it's not > + * in the same PMD as the end. > + */ > +#define ADDR_AFTER_NEXT(addr, vma) \ > + ((vma)->vm_next && (addr) > (PMD_MASK & (vma)->vm_next->vm_start)) > + > +static inline void try_to_align_end(unsigned long *len, > + struct vm_area_struct *old, unsigned long *old_addr, > + struct vm_area_struct *new, unsigned long *new_addr) > +{ > + if (*old_addr < old->vm_end) > + return; > + > + if (ADDR_AFTER_NEXT(*old_addr + *len, old)) > + return; > + > + if (ADDR_AFTER_NEXT(*new_addr + *len, new)) > + return; > + > + /* Mutual alignment means this is same for new/old addr */ > + *len = ALIGN(*new_addr + *len, PMD_SIZE) - *new_addr; > +} > + > +/* > + * The PMD move case is much more efficient, so if we have the > + * mutually aligned case, try to see if we can extend the > + * beginning and end to be aligned too. > + * > + * The pointer dereferences look bad, but with inlining, the > + * compiler will sort it out. > + */ > +static inline void try_to_align_range(unsigned long *len, > + struct vm_area_struct *old, unsigned long *old_addr, > + struct vm_area_struct *new, unsigned long *new_addr) > +{ > + if ((*old_addr ^ *new_addr) & ~PMD_MASK) > + return; > + > + try_to_align_start(len, old, old_addr, new, new_addr); > + try_to_align_end(len, old, old_addr, new, new_addr); > +} > +#else > +#define try_to_align_range(len,old,olda,new,newa) do { } while(0); > #endif > > unsigned long move_page_tables(struct vm_area_struct *vma, > @@ -272,6 +343,8 @@ unsigned long move_page_tables(struct vm_area_struct *vma, > old_addr, old_end); > mmu_notifier_invalidate_range_start(&range); > > + try_to_align_range(&len, vma, &old_addr, new_vma, &new_addr); > + > for (; old_addr < old_end; old_addr += extent, new_addr += extent) { > cond_resched(); > next = (old_addr + PMD_SIZE) & PMD_MASK; > -- > 2.27.0 > > > > > Linus > > - Naresh
