| Message ID | 20240905095216.7888-1-wangyibo@uniontech.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: move bad zone checking before getting it | expand |
On 05.09.24 11:52, Wang Yibo wrote: > When flags from gfp_zone() has an error combination, VM_BUG_ON() should firt know it before use it. s/firt/first/ Please break long lines. (checkpatch.pl should have warned you) > > Signed-off-by: Wang Yibo <wangyibo@uniontech.com> > --- > include/linux/gfp.h | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/include/linux/gfp.h b/include/linux/gfp.h > index f53f76e0b17e..ca61b2440ab3 100644 > --- a/include/linux/gfp.h > +++ b/include/linux/gfp.h > @@ -133,10 +133,11 @@ static inline enum zone_type gfp_zone(gfp_t flags) > { > enum zone_type z; > int bit = (__force int) (flags & GFP_ZONEMASK); > + VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1); Better use VM_WARN_ON_ONCE() instead while at it. > > z = (GFP_ZONE_TABLE >> (bit * GFP_ZONES_SHIFT)) & > ((1 << GFP_ZONES_SHIFT) - 1); > - VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1); > + Unrelated whitespace change. > return z; > } > But I don't see why we would want this change? It's not like the kernel would crash when calculating z. Or is there some change in behavior I am missing?
On Thu, Sep 5, 2024 at 6:22 PM David Hildenbrand <david@redhat.com> wrote: > > On 05.09.24 11:52, Wang Yibo wrote: > > When flags from gfp_zone() has an error combination, VM_BUG_ON() should firt know it before use it. > > s/firt/first/ > > Please break long lines. (checkpatch.pl should have warned you) > > > > > Signed-off-by: Wang Yibo <wangyibo@uniontech.com> > > --- > > include/linux/gfp.h | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/include/linux/gfp.h b/include/linux/gfp.h > > index f53f76e0b17e..ca61b2440ab3 100644 > > --- a/include/linux/gfp.h > > +++ b/include/linux/gfp.h > > @@ -133,10 +133,11 @@ static inline enum zone_type gfp_zone(gfp_t flags) > > { > > enum zone_type z; > > int bit = (__force int) (flags & GFP_ZONEMASK); > > + VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1); > > Better use VM_WARN_ON_ONCE() instead while at it. > > > > > z = (GFP_ZONE_TABLE >> (bit * GFP_ZONES_SHIFT)) & > > ((1 << GFP_ZONES_SHIFT) - 1); > > - VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1); > > + > > Unrelated whitespace change. > > > return z; > > } > > > > But I don't see why we would want this change? It's not like the kernel > would crash when calculating z. > > Or is there some change in behavior I am missing? On Thu, Sep 5, 2024 at 9:13 PM David Hildenbrand <david@redhat.com> wrote: > > On 05.09.24 12:48, Wang Yibo wrote: > > When flags in gfp_zone() has an error combination, > > VM_BUG_ON() should first know it before use it. > > > > Signed-off-by: Wang Yibo <wangyibo@uniontech.com> > > --- > > include/linux/gfp.h | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/include/linux/gfp.h b/include/linux/gfp.h > > index f53f76e0b17e..ca61b2440ab3 100644 > > --- a/include/linux/gfp.h > > +++ b/include/linux/gfp.h > > @@ -133,10 +133,11 @@ static inline enum zone_type gfp_zone(gfp_t flags) > > { > > enum zone_type z; > > int bit = (__force int) (flags & GFP_ZONEMASK); > > + VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1); > > > > z = (GFP_ZONE_TABLE >> (bit * GFP_ZONES_SHIFT)) & > > ((1 << GFP_ZONES_SHIFT) - 1); > > - VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1); > > + > > I'm afraid you either missed half my review comments or your answer to > my mail did not make it to my inbox. I did not read your first email carefully,Sorry for that. I will reply to your comments based on your last email. > > -- > Cheers, > > David / dhildenb > > > -- > Cheers, > > David / dhildenb >
On Thu, Sep 5, 2024 at 6:22 PM David Hildenbrand <david@redhat.com> wrote: > > On 05.09.24 11:52, Wang Yibo wrote: > > When flags from gfp_zone() has an error combination, VM_BUG_ON() should firt know it before use it. > > s/firt/first/ > > Please break long lines. (checkpatch.pl should have warned you) I will change it. > > > > > Signed-off-by: Wang Yibo <wangyibo@uniontech.com> > > --- > > include/linux/gfp.h | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/include/linux/gfp.h b/include/linux/gfp.h > > index f53f76e0b17e..ca61b2440ab3 100644 > > --- a/include/linux/gfp.h > > +++ b/include/linux/gfp.h > > @@ -133,10 +133,11 @@ static inline enum zone_type gfp_zone(gfp_t flags) > > { > > enum zone_type z; > > int bit = (__force int) (flags & GFP_ZONEMASK); > > + VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1); > > Better use VM_WARN_ON_ONCE() instead while at it. Although I do not know what results BAD ZONE flags combinations will cause, I think maybe a BUG is necessary for security ? > > > > > z = (GFP_ZONE_TABLE >> (bit * GFP_ZONES_SHIFT)) & > > ((1 << GFP_ZONES_SHIFT) - 1); > > - VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1); > > + > > Unrelated whitespace change. I will change it. > > > return z; > > } > > > > But I don't see why we would want this change? It's not like the kernel > would crash when calculating z. > > Or is there some change in behavior I am missing? I just think flags checking should precede using it logically, when I review these partial codes. So I submit this patch, there is no other reason. > > -- > Cheers, > > David / dhildenb >
diff --git a/include/linux/gfp.h b/include/linux/gfp.h index f53f76e0b17e..ca61b2440ab3 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -133,10 +133,11 @@ static inline enum zone_type gfp_zone(gfp_t flags) { enum zone_type z; int bit = (__force int) (flags & GFP_ZONEMASK); + VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1); z = (GFP_ZONE_TABLE >> (bit * GFP_ZONES_SHIFT)) & ((1 << GFP_ZONES_SHIFT) - 1); - VM_BUG_ON((GFP_ZONE_BAD >> bit) & 1); + return z; }
When flags from gfp_zone() has an error combination, VM_BUG_ON() should firt know it before use it. Signed-off-by: Wang Yibo <wangyibo@uniontech.com> --- include/linux/gfp.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)