From: Vivek Kasireddy Date: Wed, 18 Jun 2025 05:30:53 +0000 (-0700) Subject: mm/hugetlb: make hugetlb_reserve_pages() return nr of entries updated X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=986f5f2b4be3b7eab9ecd85c472d03a2191d6fc0;p=thirdparty%2Fkernel%2Flinux.git mm/hugetlb: make hugetlb_reserve_pages() return nr of entries updated Patch series "mm/memfd: Reserve hugetlb folios before allocation", v4. There are cases when we try to pin a folio but discover that it has not been faulted-in. So, we try to allocate it in memfd_alloc_folio() but the allocation request may not succeed if there are no active reservations in the system at that instant. Therefore, making a reservation (by calling hugetlb_reserve_pages()) associated with the allocation will ensure that our request would not fail due to lack of reservations. This will also ensure that proper region/subpool accounting is done with our allocation. This patch (of 3): Currently, hugetlb_reserve_pages() returns a bool to indicate whether the reservation map update for the range [from, to] was successful or not. This is not sufficient for the case where the caller needs to determine how many entries were updated for the range. Therefore, have hugetlb_reserve_pages() return the number of entries updated in the reservation map associated with the range [from, to]. Also, update the callers of hugetlb_reserve_pages() to handle the new return value. Link: https://lkml.kernel.org/r/20250618053415.1036185-1-vivek.kasireddy@intel.com Link: https://lkml.kernel.org/r/20250618053415.1036185-2-vivek.kasireddy@intel.com Signed-off-by: Vivek Kasireddy Cc: Steve Sistare Cc: Muchun Song Cc: David Hildenbrand Cc: Gerd Hoffmann Cc: Oscar Salvador Signed-off-by: Andrew Morton --- diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index e4de5425838d9..00b2d1a032fdb 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -150,10 +150,10 @@ static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma) if (inode->i_flags & S_PRIVATE) vm_flags |= VM_NORESERVE; - if (!hugetlb_reserve_pages(inode, + if (hugetlb_reserve_pages(inode, vma->vm_pgoff >> huge_page_order(h), len >> huge_page_shift(h), vma, - vm_flags)) + vm_flags) < 0) goto out; ret = 0; @@ -1561,9 +1561,9 @@ struct file *hugetlb_file_setup(const char *name, size_t size, inode->i_size = size; clear_nlink(inode); - if (!hugetlb_reserve_pages(inode, 0, + if (hugetlb_reserve_pages(inode, 0, size >> huge_page_shift(hstate_inode(inode)), NULL, - acctflag)) + acctflag) < 0) file = ERR_PTR(-ENOMEM); else file = alloc_file_pseudo(inode, mnt, name, O_RDWR, diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 42f374e828a2a..d8310b0f36ddb 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -149,7 +149,7 @@ int hugetlb_mfill_atomic_pte(pte_t *dst_pte, uffd_flags_t flags, struct folio **foliop); #endif /* CONFIG_USERFAULTFD */ -bool hugetlb_reserve_pages(struct inode *inode, long from, long to, +long hugetlb_reserve_pages(struct inode *inode, long from, long to, struct vm_area_struct *vma, vm_flags_t vm_flags); long hugetlb_unreserve_pages(struct inode *inode, long start, long end, diff --git a/mm/hugetlb.c b/mm/hugetlb.c index c7ba95030241d..e1570735012a4 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -7244,8 +7244,15 @@ long hugetlb_change_protection(struct vm_area_struct *vma, return pages > 0 ? (pages << h->order) : pages; } -/* Return true if reservation was successful, false otherwise. */ -bool hugetlb_reserve_pages(struct inode *inode, +/* + * Update the reservation map for the range [from, to]. + * + * Returns the number of entries that would be added to the reservation map + * associated with the range [from, to]. This number is greater or equal to + * zero. -EINVAL or -ENOMEM is returned in case of any errors. + */ + +long hugetlb_reserve_pages(struct inode *inode, long from, long to, struct vm_area_struct *vma, vm_flags_t vm_flags) @@ -7260,7 +7267,7 @@ bool hugetlb_reserve_pages(struct inode *inode, /* This should never happen */ if (from > to) { VM_WARN(1, "%s called with a negative range\n", __func__); - return false; + return -EINVAL; } /* @@ -7275,7 +7282,7 @@ bool hugetlb_reserve_pages(struct inode *inode, * without using reserves */ if (vm_flags & VM_NORESERVE) - return true; + return 0; /* * Shared mappings base their reservation on the number of pages that @@ -7382,7 +7389,7 @@ bool hugetlb_reserve_pages(struct inode *inode, hugetlb_cgroup_put_rsvd_cgroup(h_cg); } } - return true; + return chg; out_put_pages: spool_resv = chg - gbl_reserve; @@ -7410,7 +7417,7 @@ out_err: kref_put(&resv_map->refs, resv_map_release); set_vma_resv_map(vma, NULL); } - return false; + return chg < 0 ? chg : add < 0 ? add : -EINVAL; } long hugetlb_unreserve_pages(struct inode *inode, long start, long end,