mpol_create builds a mempolicy based on mode, nmask and maxnode. mpol_create is exposed for use in memfd_restricted_bind() in a later patch. Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx> --- include/linux/mempolicy.h | 2 ++ mm/mempolicy.c | 39 +++++++++++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+) diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h index 9a2a2dd95432..15facd9de087 100644 --- a/include/linux/mempolicy.h +++ b/include/linux/mempolicy.h @@ -125,6 +125,8 @@ struct shared_policy { }; int vma_dup_policy(struct vm_area_struct *src, struct vm_area_struct *dst); +struct mempolicy *mpol_create( + unsigned long mode, const unsigned long __user *nmask, unsigned long maxnode) void mpol_shared_policy_init(struct shared_policy *sp, struct mempolicy *mpol); int __mpol_set_shared_policy(struct shared_policy *info, struct mempolicy *mpol, unsigned long pgoff_start, unsigned long npages); diff --git a/mm/mempolicy.c b/mm/mempolicy.c index f3fa5494e4a8..f4fe241c17ff 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -3181,3 +3181,42 @@ void mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol) p += scnprintf(p, buffer + maxlen - p, ":%*pbl", nodemask_pr_args(&nodes)); } + +/** + * mpol_create - build mempolicy based on mode, nmask and maxnode + * @mode: policy mode, as in MPOL_MODE_FLAGS + * @nmask: node mask from userspace + * @maxnode: number of valid bits in nmask + * + * Will allocate a new struct mempolicy that has to be released with + * mpol_put. Will also take and release the write lock mmap_lock in current->mm. + */ +struct mempolicy *mpol_create( + unsigned long mode, const unsigned long __user *nmask, unsigned long maxnode) +{ + int err; + unsigned short mode_flags; + nodemask_t nodes; + int lmode = mode; + struct mempolicy *mpol; + + err = sanitize_mpol_flags(&lmode, &mode_flags); + if (err) + return ERR_PTR(err); + + err = get_nodes(&nodes, nmask, maxnode); + if (err) + return ERR_PTR(err); + + mpol = mpol_new(mode, mode_flags, &nodes); + if (IS_ERR(mpol)) + return mpol; + + err = mpol_init_from_nodemask(mpol, &nodes, true); + if (err) { + mpol_put(mpol); + return ERR_PTR(err); + } + + return mpol; +} -- 2.40.0.634.g4ca3ef3211-goog