| Message ID | 20240724085544.299090-5-21cnbao@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: clarify nofail memory allocation | expand |
On Wed 24-07-24 20:55:43, Barry Song wrote: > From: Barry Song <v-songbaohua@oppo.com> > > Introducing GFP_NOFAIL and gradually increasing enforcement to prevent > direct use of __GFP_NOFAIL which might be misused within non-sleepable > contexts with GFP_ATOMIC and GFP_NOWAIT. I do not think this makes sense without removing __GFP_NOFAIL and changing existing users because a new flag will very likely not be used and therefore it will not achieve the ultimate goal to remove a potential abuse. > Signed-off-by: Barry Song <v-songbaohua@oppo.com> > --- > include/linux/gfp_types.h | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/include/linux/gfp_types.h b/include/linux/gfp_types.h > index 0dad2c7914be..1666db74f25c 100644 > --- a/include/linux/gfp_types.h > +++ b/include/linux/gfp_types.h > @@ -339,6 +339,10 @@ enum { > * recurse into the FS layer with a short explanation why. All allocation > * requests will inherit GFP_NOFS implicitly. > * > + * %GFP_NOFAIL employs direct memory reclaim and continuously retries until > + * successful memory allocation. It should never be used in contexts where > + * sleeping is not allowed. > + * > * %GFP_USER is for userspace allocations that also need to be directly > * accessibly by the kernel or hardware. It is typically used by hardware > * for buffers that are mapped to userspace (e.g. graphics) that hardware > @@ -378,6 +382,7 @@ enum { > #define GFP_NOWAIT (__GFP_KSWAPD_RECLAIM | __GFP_NOWARN) > #define GFP_NOIO (__GFP_RECLAIM) > #define GFP_NOFS (__GFP_RECLAIM | __GFP_IO) > +#define GFP_NOFAIL (__GFP_RECLAIM | __GFP_NOFAIL) > #define GFP_USER (__GFP_RECLAIM | __GFP_IO | __GFP_FS | __GFP_HARDWALL) > #define GFP_DMA __GFP_DMA > #define GFP_DMA32 __GFP_DMA32 > -- > 2.34.1
diff --git a/include/linux/gfp_types.h b/include/linux/gfp_types.h index 0dad2c7914be..1666db74f25c 100644 --- a/include/linux/gfp_types.h +++ b/include/linux/gfp_types.h @@ -339,6 +339,10 @@ enum { * recurse into the FS layer with a short explanation why. All allocation * requests will inherit GFP_NOFS implicitly. * + * %GFP_NOFAIL employs direct memory reclaim and continuously retries until + * successful memory allocation. It should never be used in contexts where + * sleeping is not allowed. + * * %GFP_USER is for userspace allocations that also need to be directly * accessibly by the kernel or hardware. It is typically used by hardware * for buffers that are mapped to userspace (e.g. graphics) that hardware @@ -378,6 +382,7 @@ enum { #define GFP_NOWAIT (__GFP_KSWAPD_RECLAIM | __GFP_NOWARN) #define GFP_NOIO (__GFP_RECLAIM) #define GFP_NOFS (__GFP_RECLAIM | __GFP_IO) +#define GFP_NOFAIL (__GFP_RECLAIM | __GFP_NOFAIL) #define GFP_USER (__GFP_RECLAIM | __GFP_IO | __GFP_FS | __GFP_HARDWALL) #define GFP_DMA __GFP_DMA #define GFP_DMA32 __GFP_DMA32