FAILED: patch "[PATCH] userfaultfd: fix PTE unmapping stack-allocated PTE copies" failed to apply to 6.13-stable tree - Linux-stable-mirror

9 Mar 2025

The patch below does not apply to the 6.13-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to stable@vger.kernel.org.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.13.y
git checkout FETCH_HEAD
git cherry-pick -x 927e926d72d9155fde3264459fe9bfd7b5e40d28
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025030947-disloyal-bust-0d23@gregkh' --subject-prefix 'PATCH 6.13.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 927e926d72d9155fde3264459fe9bfd7b5e40d28 Mon Sep 17 00:00:00 2001
From: Suren Baghdasaryan surenb@google.com
Date: Wed, 26 Feb 2025 10:55:09 -0800
Subject: [PATCH] userfaultfd: fix PTE unmapping stack-allocated PTE copies
Current implementation of move_pages_pte() copies source and destination
PTEs in order to detect concurrent changes to PTEs involved in the move.
However these copies are also used to unmap the PTEs, which will fail if
CONFIG_HIGHPTE is enabled because the copies are allocated on the stack.
Fix this by using the actual PTEs which were kmap()ed.
Link: https://lkml.kernel.org/r/20250226185510.2732648-3-surenb@google.com
Fixes: adef440691ba ("userfaultfd: UFFDIO_MOVE uABI")
Signed-off-by: Suren Baghdasaryan surenb@google.com
Reported-by: Peter Xu peterx@redhat.com
Reviewed-by: Peter Xu peterx@redhat.com
Cc: Andrea Arcangeli aarcange@redhat.com
Cc: Barry Song 21cnbao@gmail.com
Cc: Barry Song v-songbaohua@oppo.com
Cc: David Hildenbrand david@redhat.com
Cc: Hugh Dickins hughd@google.com
Cc: Jann Horn jannh@google.com
Cc: Kalesh Singh kaleshsingh@google.com
Cc: Liam R. Howlett Liam.Howlett@Oracle.com
Cc: Lokesh Gidra lokeshgidra@google.com
Cc: Lorenzo Stoakes lorenzo.stoakes@oracle.com
Cc: Matthew Wilcow (Oracle) willy@infradead.org
Cc: stable@vger.kernel.org
Signed-off-by: Andrew Morton akpm@linux-foundation.org

diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index f5c6b3454f76..d06453fa8aba 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -1290,8 +1290,8 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd,
    		spin_unlock(src_ptl);
if (!locked) {
-				pte_unmap(&orig_src_pte);
-				pte_unmap(&orig_dst_pte);
+				pte_unmap(src_pte);
+				pte_unmap(dst_pte);
    			src_pte = dst_pte = NULL;
    			/* now we can block and wait */
    			folio_lock(src_folio);
@@ -1307,8 +1307,8 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd,
    	/* at this point we have src_folio locked */
    	if (folio_test_large(src_folio)) {
    		/* split_folio() can block */
-			pte_unmap(&orig_src_pte);
-			pte_unmap(&orig_dst_pte);
+			pte_unmap(src_pte);
+			pte_unmap(dst_pte);
    		src_pte = dst_pte = NULL;
    		err = split_folio(src_folio);
    		if (err)
@@ -1333,8 +1333,8 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd,
    			goto out;
    		}
    		if (!anon_vma_trylock_write(src_anon_vma)) {
-				pte_unmap(&orig_src_pte);
-				pte_unmap(&orig_dst_pte);
+				pte_unmap(src_pte);
+				pte_unmap(dst_pte);
    			src_pte = dst_pte = NULL;
    			/* now we can block and wait */
    			anon_vma_lock_write(src_anon_vma);
@@ -1352,8 +1352,8 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd,
    	entry = pte_to_swp_entry(orig_src_pte);
    	if (non_swap_entry(entry)) {
    		if (is_migration_entry(entry)) {
-				pte_unmap(&orig_src_pte);
-				pte_unmap(&orig_dst_pte);
+				pte_unmap(src_pte);
+				pte_unmap(dst_pte);
    			src_pte = dst_pte = NULL;
    			migration_entry_wait(mm, src_pmd, src_addr);
    			err = -EAGAIN;
@@ -1396,8 +1396,8 @@ static int move_pages_pte(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd,
    		src_folio = folio;
    		src_folio_pte = orig_src_pte;
    		if (!folio_trylock(src_folio)) {
-				pte_unmap(&orig_src_pte);
-				pte_unmap(&orig_dst_pte);
+				pte_unmap(src_pte);
+				pte_unmap(dst_pte);
    			src_pte = dst_pte = NULL;
    			put_swap_device(si);
    			si = NULL;

    