| Message ID | 20230302232758.888157-4-mcgrof@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | tmpfs: add the option to disable swap | expand |
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>
On Thu, Mar 2, 2023 at 3:28 PM Luis Chamberlain <mcgrof@kernel.org> 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> Nice cleanup. Reviewed-by: Yosry Ahmed <yosryahmed@google.com> > --- > 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) { > + WARN_ON_ONCE(1); /* Still happens? Tell us about it! */ > + 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 > -- > 2.39.1 >
On Mon, Mar 06, 2023 at 03:01:52PM +0100, David Hildenbrand wrote: > On 03.03.23 00:27, Luis Chamberlain wrote: > > @@ -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. Good call, will add that to v2. > Acked-by: David Hildenbrand <david@redhat.com> Great thanks, Luis
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) { + WARN_ON_ONCE(1); /* Still happens? Tell us about it! */ + 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
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(-)