On 24/06/2024 18:26, Hugh Dickins wrote:
On Mon, 24 Jun 2024, Usama Arif wrote:
On 24/06/2024 15:05, Yosry Ahmed wrote:
On Mon, Jun 24, 2024 at 1:49 AM kernel test robot <oliver.sang@xxxxxxxxx>
wrote:
Hello,
kernel test robot noticed
"WARNING:at_mm/page_alloc.c:#__alloc_pages_noprof" on:
commit: 0fa2857d23aa170e5e28d13c467b303b0065aad8 ("mm: store zero pages to
be swapped out in a bitmap")
https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
This is coming from WARN_ON_ONCE_GFP(order > MAX_PAGE_ORDER, gfp), and
is triggered by the new bitmap_zalloc() call in the swapon path. For a
sufficiently large swapfile, bitmap_zalloc() (which uses kmalloc()
under the hood) cannot be used to allocate the bitmap.
Usama, I think we want to use a variant of kvmalloc() here.
Yes, I hit the same problem with swapon in my testing,
and had been intending to send a patch.
Yes, just testing with below diff now. The patch is not in mm-stable yet, so
will just send another revision with below diff included. Thanks!
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 0b8270359bcf..2263f71baa31 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -2643,7 +2643,7 @@ SYSCALL_DEFINE1(swapoff, const char __user *,
specialfile)
free_percpu(p->cluster_next_cpu);
p->cluster_next_cpu = NULL;
vfree(swap_map);
- bitmap_free(p->zeromap);
+ kvfree(p->zeromap);
Yes.
kvfree(cluster_info);
/* Destroy swap account information */
swap_cgroup_swapoff(p->type);
@@ -3170,7 +3170,7 @@ SYSCALL_DEFINE2(swapon, const char __user *,
specialfile, int, swap_flags)
goto bad_swap_unlock_inode;
}
- p->zeromap = bitmap_zalloc(maxpages, GFP_KERNEL);
+ p->zeromap = kvzalloc(DIV_ROUND_UP(maxpages, 8), GFP_KERNEL);
No, 8 is not right for 32-bit kernels. I think you want
p->zeromap = kvzalloc(BITS_TO_LONGS(maxpages), GFP_KERNEL);
but please check it carefully, I'm easily confused by such conversions.
Hugh
Ah yes, didnt take into account 32-bit kernel. I think its supposed to be
p->zeromap = kvzalloc(BITS_TO_LONGS(maxpages) * sizeof(unsigned long),
GFP_KERNEL);
if using BITS_TO_LONGS.
Will wait sometime incase there are more comments and will send out
another version.
Thanks!
if (!p->zeromap) {
error = -ENOMEM;
goto bad_swap_unlock_inode;
