On Wed, Jul 24, 2024 at 9:53 PM Vlastimil Babka <vbabka@xxxxxxx> wrote: > > On 7/24/24 10:55 AM, Barry Song wrote: > > From: Barry Song <v-songbaohua@xxxxxxxx> > > > > GFP_NOFAIL includes the meaning of block and direct reclamation, which > > is essential for a true no-fail allocation. We are gradually starting > > to enforce this block semantics to prevent the potential misuse of > > __GFP_NOFAIL in atomic contexts in the future. > > > > A typical example of incorrect usage is in VDPA, where GFP_ATOMIC > > and __GFP_NOFAIL are used together. > > > > [RFC]: This patch seems quite large; I don't mind splitting it into > > multiple patches for different subsystems after patches 1 ~ 4 have > > been applied. > > > > Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx> > > > > diff --git a/arch/powerpc/sysdev/xive/common.c b/arch/powerpc/sysdev/xive/common.c > > index fa01818c1972..29eaf8b84b52 100644 > > --- a/arch/powerpc/sysdev/xive/common.c > > +++ b/arch/powerpc/sysdev/xive/common.c > > @@ -1146,7 +1146,7 @@ static int __init xive_init_ipis(void) > > if (!ipi_domain) > > goto out_free_fwnode; > > > > - xive_ipis = kcalloc(nr_node_ids, sizeof(*xive_ipis), GFP_KERNEL | __GFP_NOFAIL); > > + xive_ipis = kcalloc(nr_node_ids, sizeof(*xive_ipis), GFP_KERNEL | GFP_NOFAIL); > > This (and others) doesn't look great. Normally there's just one GFP_MAIN > that combines several commonly used together flags internally, with possibly > some | __GFP_EXTRA addition for less common modifications. Now you're > combining two GFP_MAIN's and that's just confusing. This is true, but I assume this won't incur overhead at runtime since the compiler resolves GFP_KERNEL | GFP_NOFAIL at compile-time. Only readers might find some bits are duplicated OR twice? > > So if we want to go this way, you'd need e.g. > > GFP_KERNEL_NOFAIL which is GFP_KERNEL | __GFP_NOFAIL I actually considered this, but it doesn't always work because we have many cases: variable |= __GFP_NOFAIL. > > And probably also GFP_NOFS_NOFAIL and GFP_NOIO_NOFAIL (sigh). > > > if (!xive_ipis) > > goto out_free_domain; >
