On Tue, May 28, 2024 at 10:53:23PM +0200, Oscar Salvador wrote: > sysbot reported a splat [1] on __unmap_hugepage_range(). > This is because vma_needs_reservation() can return -ENOMEM if > allocate_file_region_entries() fails to allocate the file_region struct for > the reservation. > Check for that and do not call vma_add_reservation() if that is the case, > otherwise region_abort() and region_del() will see that we do not have any > file_regions. > > If we detect that vma_needs_reservation() returned -ENOMEM, we clear the > hugetlb_restore_reserve flag as if this reservation was still consumed, > so free_huge_folio() will not increment the resv count. > > [1] https://lore.kernel.org/linux-mm/0000000000004096100617c58d54@xxxxxxxxxx/T/#ma5983bc1ab18a54910da83416b3f89f3c7ee43aa > > Fixes: df7a6d1f6405 ("mm/hugetlb: restore the reservation if needed") > Reported-and-tested-by: syzbot+d3fe2dc5ffe9380b714b@xxxxxxxxxxxxxxxxxxxxxxxxx > Closes: https://lore.kernel.org/linux-mm/0000000000004096100617c58d54@xxxxxxxxxx/ > Signed-off-by: Oscar Salvador <osalvador@xxxxxxx> > --- > mm/hugetlb.c | 16 ++++++++++++++-- > 1 file changed, 14 insertions(+), 2 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 6be78e7d4f6e..f35abff8be60 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -5768,8 +5768,20 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma, > * do_exit() will not see it, and will keep the reservation > * forever. > */ > - if (adjust_reservation && vma_needs_reservation(h, vma, address)) > - vma_add_reservation(h, vma, address); > + if (adjust_reservation) { > + int rc = vma_needs_reservation(h, vma, address); vma_needs_reservation returns a long. static long vma_needs_reservation(struct hstate *h, struct vm_area_struct *vma, unsigned long addr) Other than that, this is reviewed. Reviewed-by: Breno Leitao <leitao@xxxxxxxxxx> Thanks for fixing it.
