From ddc1a5cbc05dc62743a2f409b96faa5cf95ba064 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Thu, 19 Oct 2023 13:39:08 -0700 Subject: mempolicy: alloc_pages_mpol() for NUMA policy without vma Shrink shmem's stack usage by eliminating the pseudo-vma from its folio allocation. alloc_pages_mpol(gfp, order, pol, ilx, nid) becomes the principal actor for passing mempolicy choice down to __alloc_pages(), rather than vma_alloc_folio(gfp, order, vma, addr, hugepage). vma_alloc_folio() and alloc_pages() remain, but as wrappers around alloc_pages_mpol(). alloc_pages_bulk_*() untouched, except to provide the additional args to policy_nodemask(), which subsumes policy_node(). Cleanup throughout, cutting out some unhelpful "helpers". It would all be much simpler without MPOL_INTERLEAVE, but that adds a dynamic to the constant mpol: complicated by v3.6 commit 09c231cb8bfd ("tmpfs: distribute interleave better across nodes"), which added ino bias to the interleave, hidden from mm/mempolicy.c until this commit. Hence "ilx" throughout, the "interleave index". Originally I thought it could be done just with nid, but that's wrong: the nodemask may come from the shared policy layer below a shmem vma, or it may come from the task layer above a shmem vma; and without the final nodemask then nodeid cannot be decided. And how ilx is applied depends also on page order. The interleave index is almost always irrelevant unless MPOL_INTERLEAVE: with one exception in alloc_pages_mpol(), where the NO_INTERLEAVE_INDEX passed down from vma-less alloc_pages() is also used as hint not to use THP-style hugepage allocation - to avoid the overhead of a hugepage arg (though I don't understand why we never just added a GFP bit for THP - if it actually needs a different allocation strategy from other pages of the same order). vma_alloc_folio() still carries its hugepage arg here, but it is not used, and should be removed when agreed. get_vma_policy() no longer allows a NULL vma: over time I believe we've eradicated all the places which used to need it e.g. swapoff and madvise used to pass NULL vma to read_swap_cache_async(), but now know the vma. [hughd@google.com: handle NULL mpol being passed to __read_swap_cache_async()] Link: https://lkml.kernel.org/r/ea419956-4751-0102-21f7-9c93cb957892@google.com Link: https://lkml.kernel.org/r/74e34633-6060-f5e3-aee-7040d43f2e93@google.com Link: https://lkml.kernel.org/r/1738368e-bac0-fd11-ed7f-b87142a939fe@google.com Signed-off-by: Hugh Dickins Cc: Andi Kleen Cc: Christoph Lameter Cc: David Hildenbrand Cc: Greg Kroah-Hartman Cc: Huang Ying Cc: Kefeng Wang Cc: Matthew Wilcox (Oracle) Cc: Mel Gorman Cc: Michal Hocko Cc: Mike Kravetz Cc: Nhat Pham Cc: Sidhartha Kumar Cc: Suren Baghdasaryan Cc: Tejun heo Cc: Vishal Moola (Oracle) Cc: Yang Shi Cc: Yosry Ahmed Cc: Domenico Cerasuolo Cc: Johannes Weiner Signed-off-by: Andrew Morton --- ipc/shm.c | 21 ++++++++------------- 1 file changed, 8 insertions(+), 13 deletions(-) (limited to 'ipc') diff --git a/ipc/shm.c b/ipc/shm.c index 576a543b7cff..222aaf035afb 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -562,30 +562,25 @@ static unsigned long shm_pagesize(struct vm_area_struct *vma) } #ifdef CONFIG_NUMA -static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new) +static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol) { - struct file *file = vma->vm_file; - struct shm_file_data *sfd = shm_file_data(file); + struct shm_file_data *sfd = shm_file_data(vma->vm_file); int err = 0; if (sfd->vm_ops->set_policy) - err = sfd->vm_ops->set_policy(vma, new); + err = sfd->vm_ops->set_policy(vma, mpol); return err; } static struct mempolicy *shm_get_policy(struct vm_area_struct *vma, - unsigned long addr) + unsigned long addr, pgoff_t *ilx) { - struct file *file = vma->vm_file; - struct shm_file_data *sfd = shm_file_data(file); - struct mempolicy *pol = NULL; + struct shm_file_data *sfd = shm_file_data(vma->vm_file); + struct mempolicy *mpol = vma->vm_policy; if (sfd->vm_ops->get_policy) - pol = sfd->vm_ops->get_policy(vma, addr); - else if (vma->vm_policy) - pol = vma->vm_policy; - - return pol; + mpol = sfd->vm_ops->get_policy(vma, addr, ilx); + return mpol; } #endif -- cgit