| Message ID | 462ff52742a1fcc95a69778685737f723ee4dfb3.1648400273.git.andreyknvl@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm, kasan: fix __GFP_BITS_SHIFT definition breaking LOCKDEP | expand |
On 3/27/22 19:00, andrey.konovalov@linux.dev wrote: > From: Andrey Konovalov <andreyknvl@google.com> > > KASAN changes that added new GFP flags mistakenly updated __GFP_BITS_SHIFT > as the total number of GFP bits instead of as a shift used to define > __GFP_BITS_MASK. > > This broke LOCKDEP, as __GFP_BITS_MASK now gets the 25th bit enabled > instead of the 28th for __GFP_NOLOCKDEP. > > Update __GFP_BITS_SHIFT to always count KASAN GFP bits. > > In the future, we could handle all combinations of KASAN and LOCKDEP to > occupy as few bits as possible. For now, we have enough GFP bits to be > inefficient in this quick fix. > > Fixes: 9353ffa6e9e9 ("kasan, page_alloc: allow skipping memory init for HW_TAGS") > Fixes: 53ae233c30a6 ("kasan, page_alloc: allow skipping unpoisoning for HW_TAGS") > Fixes: f49d9c5bb15c ("kasan, mm: only define ___GFP_SKIP_KASAN_POISON with HW_TAGS") > Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> > --- > include/linux/gfp.h | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/include/linux/gfp.h b/include/linux/gfp.h > index 0fa17fb85de5..761f8f1885c7 100644 > --- a/include/linux/gfp.h > +++ b/include/linux/gfp.h > @@ -264,9 +264,7 @@ struct vm_area_struct; > #define __GFP_NOLOCKDEP ((__force gfp_t)___GFP_NOLOCKDEP) > > /* Room for N __GFP_FOO bits */ > -#define __GFP_BITS_SHIFT (24 + \ > - 3 * IS_ENABLED(CONFIG_KASAN_HW_TAGS) + \ > - IS_ENABLED(CONFIG_LOCKDEP)) > +#define __GFP_BITS_SHIFT (27 + IS_ENABLED(CONFIG_LOCKDEP)) > #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1)) > > /**
On 2022-03-27 19:00:23 [+0200], andrey.konovalov@linux.dev wrote: > From: Andrey Konovalov <andreyknvl@google.com> > > KASAN changes that added new GFP flags mistakenly updated __GFP_BITS_SHIFT > as the total number of GFP bits instead of as a shift used to define > __GFP_BITS_MASK. > > This broke LOCKDEP, as __GFP_BITS_MASK now gets the 25th bit enabled > instead of the 28th for __GFP_NOLOCKDEP. > > Update __GFP_BITS_SHIFT to always count KASAN GFP bits. > > In the future, we could handle all combinations of KASAN and LOCKDEP to > occupy as few bits as possible. For now, we have enough GFP bits to be > inefficient in this quick fix. > > Fixes: 9353ffa6e9e9 ("kasan, page_alloc: allow skipping memory init for HW_TAGS") > Fixes: 53ae233c30a6 ("kasan, page_alloc: allow skipping unpoisoning for HW_TAGS") > Fixes: f49d9c5bb15c ("kasan, mm: only define ___GFP_SKIP_KASAN_POISON with HW_TAGS") > Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Sebastian
diff --git a/include/linux/gfp.h b/include/linux/gfp.h index 0fa17fb85de5..761f8f1885c7 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -264,9 +264,7 @@ struct vm_area_struct; #define __GFP_NOLOCKDEP ((__force gfp_t)___GFP_NOLOCKDEP) /* Room for N __GFP_FOO bits */ -#define __GFP_BITS_SHIFT (24 + \ - 3 * IS_ENABLED(CONFIG_KASAN_HW_TAGS) + \ - IS_ENABLED(CONFIG_LOCKDEP)) +#define __GFP_BITS_SHIFT (27 + IS_ENABLED(CONFIG_LOCKDEP)) #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1)) /**