Commit 6ab70303 authored by Mike Rapoport (Microsoft)'s avatar Mike Rapoport (Microsoft) Committed by Andrew Morton
Browse files

userfaultfd: mfill_atomic(): remove retry logic 

Since __mfill_atomic_pte() handles the retry for both anonymous and shmem,
there is no need to retry copying the date from the userspace in the loop
in mfill_atomic().

Drop the retry logic from mfill_atomic().

[rppt@kernel.org: remove safety measure of not returning ENOENT from _copy]
  Link: https://lore.kernel.org/ac5zcDUY8CFHr6Lw@kernel.org
Link: https://lore.kernel.org/20260402041156.1377214-12-rppt@kernel.org


Signed-off-by: default avatarMike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrei Vagin <avagin@google.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand (Arm) <david@kernel.org>
Cc: Harry Yoo <harry.yoo@oracle.com>
Cc: Harry Yoo (Oracle) <harry@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nikita Kalyazin <kalyazin@amazon.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Carlier <devnexen@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent f74991b4

mm/userfaultfd.c

+0 −27
Original line number Diff line number Diff line
@@ -29,7 +29,6 @@ struct mfill_state { 
	struct vm_area_struct *vma;

	unsigned long src_addr;

	unsigned long dst_addr;

	struct folio *folio;

	pmd_t *pmd;

};
@@ -531,9 +530,6 @@ static int __mfill_atomic_pte(struct mfill_state *state, 
		ops->filemap_remove(folio, state->vma);

err_folio_put:

	folio_put(folio);

	/* Don't return -ENOENT so that our caller won't retry */

	if (ret == -ENOENT)

		ret = -EFAULT;

	return ret;

}
@@ -899,7 +895,6 @@ static __always_inline ssize_t mfill_atomic(struct userfaultfd_ctx *ctx, 
	VM_WARN_ON_ONCE(src_start + len <= src_start);

	VM_WARN_ON_ONCE(dst_start + len <= dst_start);



retry:

	err = mfill_get_vma(&state);

	if (err)

		goto out;
@@ -926,26 +921,6 @@ static __always_inline ssize_t mfill_atomic(struct userfaultfd_ctx *ctx, 
		err = mfill_atomic_pte(&state);

		cond_resched();



		if (unlikely(err == -ENOENT)) {

			void *kaddr;



			mfill_put_vma(&state);

			VM_WARN_ON_ONCE(!state.folio);



			kaddr = kmap_local_folio(state.folio, 0);

			err = copy_from_user(kaddr,

					     (const void __user *)state.src_addr,

					     PAGE_SIZE);

			kunmap_local(kaddr);

			if (unlikely(err)) {

				err = -EFAULT;

				goto out;

			}

			flush_dcache_folio(state.folio);

			goto retry;

		} else

			VM_WARN_ON_ONCE(state.folio);



		if (!err) {

			state.dst_addr += PAGE_SIZE;

			state.src_addr += PAGE_SIZE;
@@ -960,8 +935,6 @@ static __always_inline ssize_t mfill_atomic(struct userfaultfd_ctx *ctx, 


	mfill_put_vma(&state);

out:

	if (state.folio)

		folio_put(state.folio);

	VM_WARN_ON_ONCE(copied < 0);

	VM_WARN_ON_ONCE(err > 0);

	VM_WARN_ON_ONCE(!copied && !err);