On Tue, 31 Oct 2023, Marek Marczykowski-Górecki wrote:
> On Tue, Oct 31, 2023 at 03:01:36PM +0100, Jan Kara wrote:
> > On Tue 31-10-23 04:48:44, Marek Marczykowski-Górecki wrote:
> > > Then tried:
> > > - PAGE_ALLOC_COSTLY_ORDER=4, order=4 - cannot reproduce,
> > > - PAGE_ALLOC_COSTLY_ORDER=4, order=5 - cannot reproduce,
> > > - PAGE_ALLOC_COSTLY_ORDER=4, order=6 - freeze rather quickly
> > >
> > > I've retried the PAGE_ALLOC_COSTLY_ORDER=4,order=5 case several times
> > > and I can't reproduce the issue there. I'm confused...
> >
> > And this kind of confirms that allocations > PAGE_ALLOC_COSTLY_ORDER
> > causing hangs is most likely just a coincidence. Rather something either in
> > the block layer or in the storage driver has problems with handling bios
> > with sufficiently high order pages attached. This is going to be a bit
> > painful to debug I'm afraid. How long does it take for you trigger the
> > hang? I'm asking to get rough estimate how heavy tracing we can afford so
> > that we don't overwhelm the system...
>
> Sometimes it freezes just after logging in, but in worst case it takes
> me about 10min of more or less `tar xz` + `dd`.
Hi
I would like to ask you to try this patch. Revert the changes to "order"
and "PAGE_ALLOC_COSTLY_ORDER" back to normal and apply this patch on a
clean upstream kernel.
Does it deadlock?
There is a bug in dm-crypt that it doesn't account large pages in
cc->n_allocated_pages, this patch fixes the bug.
Mikulas
---
drivers/md/dm-crypt.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
Index: linux-stable/drivers/md/dm-crypt.c
===================================================================
--- linux-stable.orig/drivers/md/dm-crypt.c 2023-10-31 16:25:09.000000000 +0100
+++ linux-stable/drivers/md/dm-crypt.c 2023-10-31 16:53:14.000000000 +0100
@@ -1700,11 +1700,16 @@ retry:
order = min(order, remaining_order);
while (order > 0) {
+ if (unlikely(percpu_counter_read_positive(&cc->n_allocated_pages) + (1 << order) > dm_crypt_pages_per_client))
+ goto decrease_order;
pages = alloc_pages(gfp_mask
| __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN | __GFP_COMP,
order);
- if (likely(pages != NULL))
+ if (likely(pages != NULL)) {
+ percpu_counter_add(&cc->n_allocated_pages, 1 << order);
goto have_pages;
+ }
+decrease_order:
order--;
}
@@ -1742,10 +1747,12 @@ static void crypt_free_buffer_pages(stru
if (clone->bi_vcnt > 0) { /* bio_for_each_folio_all crashes with an empty bio */
bio_for_each_folio_all(fi, clone) {
- if (folio_test_large(fi.folio))
+ if (folio_test_large(fi.folio)) {
+ percpu_counter_sub(&cc->n_allocated_pages, 1 << folio_order(fi.folio));
folio_put(fi.folio);
- else
+ } else {
mempool_free(&fi.folio->page, &cc->page_pool);
+ }
}
}
}
