Messages in this thread Patch in this message | | | Date | Mon, 6 Mar 2023 15:01:52 +0100 | Subject | Re: [PATCH 3/6] shmem: move reclaim check early on writepages() | From | David Hildenbrand <> |
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On 03.03.23 00:27, Luis Chamberlain wrote: > i915_gem requires huge folios to be split when swapping. > However we have check for usage of writepages() to ensure > it used only for swap purposes later. Avoid the splits if > we're not being called for reclaim, even if they should in > theory not happen. > > This makes the conditions easier to follow on shem_writepage(). > > Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> > --- > mm/shmem.c | 24 ++++++++++++------------ > 1 file changed, 12 insertions(+), 12 deletions(-) > > diff --git a/mm/shmem.c b/mm/shmem.c > index 2b9ff585a553..a5a6da51087e 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -1340,6 +1340,18 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) > swp_entry_t swap; > pgoff_t index; > > + /* > + * Our capabilities prevent regular writeback or sync from ever calling > + * shmem_writepage; but a stacking filesystem might use ->writepage of > + * its underlying filesystem, in which case tmpfs should write out to > + * swap only in response to memory pressure, and not for the writeback > + * threads or sync. > + */ > + if (!wbc->for_reclaim) {
if (WARN_ON_ONCE(!wbc->for_reclaim))
> + WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
And drop the comment :) That's what WARN_ON_ONCE is all about.
> + goto redirty; > + } > + > /* > * If /sys/kernel/mm/transparent_hugepage/shmem_enabled is "always" or > * "force", drivers/gpu/drm/i915/gem/i915_gem_shmem.c gets huge pages, > @@ -1360,18 +1372,6 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) > if (!total_swap_pages) > goto redirty; > > - /* > - * Our capabilities prevent regular writeback or sync from ever calling > - * shmem_writepage; but a stacking filesystem might use ->writepage of > - * its underlying filesystem, in which case tmpfs should write out to > - * swap only in response to memory pressure, and not for the writeback > - * threads or sync. > - */ > - if (!wbc->for_reclaim) { > - WARN_ON_ONCE(1); /* Still happens? Tell us about it! */ > - goto redirty; > - } > - > /* > * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC > * value into swapfile.c, the only way we can correctly account for a
LGTM
Acked-by: David Hildenbrand <david@redhat.com>
-- Thanks,
David / dhildenb
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