| Message ID | 1517986471-15185-4-git-send-email-wei.w.wang@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Feb 07, 2018 at 02:54:30PM +0800, Wei Wang wrote: > In some usages, e.g. virtio-balloon, a kernel module needs to know if > page poisoning is in use. This patch exposes the page_poisoning_enabled > function to kernel modules. > > Signed-off-by: Wei Wang <wei.w.wang@intel.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Michal Hocko <mhocko@kernel.org> > Cc: Michael S. Tsirkin <mst@redhat.com> > --- > mm/page_poison.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/mm/page_poison.c b/mm/page_poison.c > index e83fd44..c08d02a 100644 > --- a/mm/page_poison.c > +++ b/mm/page_poison.c > @@ -30,6 +30,11 @@ bool page_poisoning_enabled(void) > debug_pagealloc_enabled())); > } > > +/** > + * page_poisoning_enabled - check if page poisoning is enabled > + * > + * Return true if page poisoning is enabled, or false if not. > + */ > static void poison_page(struct page *page) > { > void *addr = kmap_atomic(page); > @@ -37,6 +42,7 @@ static void poison_page(struct page *page) > memset(addr, PAGE_POISON, PAGE_SIZE); > kunmap_atomic(addr); > } > +EXPORT_SYMBOL_GPL(page_poisoning_enabled); > > static void poison_pages(struct page *page, int n) > { Looks like both the comment and the export are in the wrong place. I'm a bit concerned that callers also in fact poke at the PAGE_POISON - exporting that seems to be more of an accident as it's only used without page_poisoning.c - it might be better to have page_poisoning_enabled get u8 * and set it. > -- > 2.7.4
On 02/08/2018 02:34 AM, Michael S. Tsirkin wrote: > On Wed, Feb 07, 2018 at 02:54:30PM +0800, Wei Wang wrote: >> In some usages, e.g. virtio-balloon, a kernel module needs to know if >> page poisoning is in use. This patch exposes the page_poisoning_enabled >> function to kernel modules. >> >> Signed-off-by: Wei Wang <wei.w.wang@intel.com> >> Cc: Andrew Morton <akpm@linux-foundation.org> >> Cc: Michal Hocko <mhocko@kernel.org> >> Cc: Michael S. Tsirkin <mst@redhat.com> >> --- >> mm/page_poison.c | 6 ++++++ >> 1 file changed, 6 insertions(+) >> >> diff --git a/mm/page_poison.c b/mm/page_poison.c >> index e83fd44..c08d02a 100644 >> --- a/mm/page_poison.c >> +++ b/mm/page_poison.c >> @@ -30,6 +30,11 @@ bool page_poisoning_enabled(void) >> debug_pagealloc_enabled())); >> } >> >> +/** >> + * page_poisoning_enabled - check if page poisoning is enabled >> + * >> + * Return true if page poisoning is enabled, or false if not. >> + */ >> static void poison_page(struct page *page) >> { >> void *addr = kmap_atomic(page); >> @@ -37,6 +42,7 @@ static void poison_page(struct page *page) >> memset(addr, PAGE_POISON, PAGE_SIZE); >> kunmap_atomic(addr); >> } >> +EXPORT_SYMBOL_GPL(page_poisoning_enabled); >> >> static void poison_pages(struct page *page, int n) >> { > Looks like both the comment and the export are in the wrong place. Thanks. Will be more careful. > I'm a bit concerned that callers also in fact poke at the > PAGE_POISON - exporting that seems to be more of an accident > as it's only used without page_poisoning.c - it might be > better to have page_poisoning_enabled get u8 * and set it. > PAGE_POISON is a macro defined in the header, why would callers using it be a concern? Do you suggest to have: bool page_poisoning_get(u8 *val) { if (page_poisoning_enabled()) { *val = PAGE_POISON; return true; } return false; } EXPORT_SYMBOL_GPL(page_poisoning_get); Best, Wei
On Thu, Feb 08, 2018 at 09:44:29AM +0800, Wei Wang wrote: > On 02/08/2018 02:34 AM, Michael S. Tsirkin wrote: > > On Wed, Feb 07, 2018 at 02:54:30PM +0800, Wei Wang wrote: > > > In some usages, e.g. virtio-balloon, a kernel module needs to know if > > > page poisoning is in use. This patch exposes the page_poisoning_enabled > > > function to kernel modules. > > > > > > Signed-off-by: Wei Wang <wei.w.wang@intel.com> > > > Cc: Andrew Morton <akpm@linux-foundation.org> > > > Cc: Michal Hocko <mhocko@kernel.org> > > > Cc: Michael S. Tsirkin <mst@redhat.com> > > > --- > > > mm/page_poison.c | 6 ++++++ > > > 1 file changed, 6 insertions(+) > > > > > > diff --git a/mm/page_poison.c b/mm/page_poison.c > > > index e83fd44..c08d02a 100644 > > > --- a/mm/page_poison.c > > > +++ b/mm/page_poison.c > > > @@ -30,6 +30,11 @@ bool page_poisoning_enabled(void) > > > debug_pagealloc_enabled())); > > > } > > > +/** > > > + * page_poisoning_enabled - check if page poisoning is enabled > > > + * > > > + * Return true if page poisoning is enabled, or false if not. > > > + */ > > > static void poison_page(struct page *page) > > > { > > > void *addr = kmap_atomic(page); > > > @@ -37,6 +42,7 @@ static void poison_page(struct page *page) > > > memset(addr, PAGE_POISON, PAGE_SIZE); > > > kunmap_atomic(addr); > > > } > > > +EXPORT_SYMBOL_GPL(page_poisoning_enabled); > > > static void poison_pages(struct page *page, int n) > > > { > > Looks like both the comment and the export are in the wrong place. > > Thanks. Will be more careful. > > > I'm a bit concerned that callers also in fact poke at the > > PAGE_POISON - exporting that seems to be more of an accident > > as it's only used without page_poisoning.c - it might be > > better to have page_poisoning_enabled get u8 * and set it. > > > > PAGE_POISON is a macro defined in the header, why would callers using it be > a concern? It might be a good idea to move it out of there though. > Do you suggest to have: > > bool page_poisoning_get(u8 *val) > { > if (page_poisoning_enabled()) { > *val = PAGE_POISON; > return true; > } > > return false; > } > EXPORT_SYMBOL_GPL(page_poisoning_get); > > > Best, > Wei Something like this, yes.
diff --git a/mm/page_poison.c b/mm/page_poison.c index e83fd44..c08d02a 100644 --- a/mm/page_poison.c +++ b/mm/page_poison.c @@ -30,6 +30,11 @@ bool page_poisoning_enabled(void) debug_pagealloc_enabled())); } +/** + * page_poisoning_enabled - check if page poisoning is enabled + * + * Return true if page poisoning is enabled, or false if not. + */ static void poison_page(struct page *page) { void *addr = kmap_atomic(page); @@ -37,6 +42,7 @@ static void poison_page(struct page *page) memset(addr, PAGE_POISON, PAGE_SIZE); kunmap_atomic(addr); } +EXPORT_SYMBOL_GPL(page_poisoning_enabled); static void poison_pages(struct page *page, int n) {
In some usages, e.g. virtio-balloon, a kernel module needs to know if page poisoning is in use. This patch exposes the page_poisoning_enabled function to kernel modules. Signed-off-by: Wei Wang <wei.w.wang@intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michael S. Tsirkin <mst@redhat.com> --- mm/page_poison.c | 6 ++++++ 1 file changed, 6 insertions(+)