The patch titled Subject: shmem: fix smaps BUG sleeping while atomic has been added to the -mm mm-hotfixes-unstable branch. Its filename is shmem-fix-smaps-bug-sleeping-while-atomic.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: Hugh Dickins hughd@google.com Subject: shmem: fix smaps BUG sleeping while atomic Date: Tue, 22 Aug 2023 22:14:47 -0700 (PDT)

smaps_pte_hole_lookup() is calling shmem_partial_swap_usage() with page table lock held: but shmem_partial_swap_usage() does cond_resched_rcu() if need_resched(): "BUG: sleeping function called from invalid context".

Since shmem_partial_swap_usage() is designed to count across a range, but smaps_pte_hole_lookup() only calls it for a single page slot, just break out of the loop on the last or only page, before checking need_resched().

Link: https://lkml.kernel.org/r/6fe3b3ec-abdf-332f-5c23-6a3b3a3b11a9@google.com Fixes: 230100321518 ("mm/smaps: simplify shmem handling of pte holes") Signed-off-by: Hugh Dickins hughd@google.com Acked-by: Peter Xu peterx@redhat.com Cc: stable@vger.kernel.org [5.16+] Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/shmem.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/mm/shmem.c~shmem-fix-smaps-bug-sleeping-while-atomic +++ a/mm/shmem.c @@ -806,14 +806,16 @@ unsigned long shmem_partial_swap_usage(s XA_STATE(xas, &mapping->i_pages, start); struct page *page; unsigned long swapped = 0; + unsigned long max = end - 1;

rcu_read_lock(); - xas_for_each(&xas, page, end - 1) { + xas_for_each(&xas, page, max) { if (xas_retry(&xas, page)) continue; if (xa_is_value(page)) swapped++; - + if (xas.xa_index == max) + break; if (need_resched()) { xas_pause(&xas); cond_resched_rcu(); _

Patches currently in -mm which might be from hughd@google.com are

shmem-fix-smaps-bug-sleeping-while-atomic.patch