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Wed, 25 Oct 2023 08:28:47 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20231024134637.3120277-1-surenb@google.com> <20231024134637.3120277-7-surenb@google.com> <20231025074652.44bc0eb4@meshulam.tesarici.cz> In-Reply-To: <20231025074652.44bc0eb4@meshulam.tesarici.cz> From: Suren Baghdasaryan Date: Wed, 25 Oct 2023 08:28:32 -0700 Message-ID: Subject: Re: [PATCH v2 06/39] mm: enumerate all gfp flags To: =?UTF-8?B?UGV0ciBUZXNhxZnDrWs=?= Cc: Neil Brown , akpm@linux-foundation.org, kent.overstreet@linux.dev, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, roman.gushchin@linux.dev, mgorman@suse.de, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, corbet@lwn.net, void@manifault.com, peterz@infradead.org, juri.lelli@redhat.com, ldufour@linux.ibm.com, catalin.marinas@arm.com, will@kernel.org, arnd@arndb.de, tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com, x86@kernel.org, peterx@redhat.com, david@redhat.com, axboe@kernel.dk, mcgrof@kernel.org, masahiroy@kernel.org, nathan@kernel.org, dennis@kernel.org, tj@kernel.org, muchun.song@linux.dev, rppt@kernel.org, paulmck@kernel.org, pasha.tatashin@soleen.com, yosryahmed@google.com, yuzhao@google.com, dhowells@redhat.com, hughd@google.com, andreyknvl@gmail.com, keescook@chromium.org, ndesaulniers@google.com, vvvvvv@google.com, gregkh@linuxfoundation.org, ebiggers@google.com, ytcoode@gmail.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, bristot@redhat.com, vschneid@redhat.com, cl@linux.com, penberg@kernel.org, iamjoonsoo.kim@lge.com, 42.hyeyoo@gmail.com, glider@google.com, elver@google.com, dvyukov@google.com, shakeelb@google.com, songmuchun@bytedance.com, jbaron@akamai.com, rientjes@google.com, minchan@google.com, kaleshsingh@google.com, kernel-team@android.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux.dev, linux-arch@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-modules@vger.kernel.org, kasan-dev@googlegroups.com, cgroups@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, Oct 24, 2023 at 10:47=E2=80=AFPM Petr Tesa=C5=99=C3=ADk wrote: > > On Tue, 24 Oct 2023 06:46:03 -0700 > Suren Baghdasaryan wrote: > > > Introduce GFP bits enumeration to let compiler track the number of used > > bits (which depends on the config options) instead of hardcoding them. > > That simplifies __GFP_BITS_SHIFT calculation. > > Suggested-by: Petr Tesa=C5=99=C3=ADk > > Signed-off-by: Suren Baghdasaryan > > --- > > include/linux/gfp_types.h | 90 +++++++++++++++++++++++++++------------ > > 1 file changed, 62 insertions(+), 28 deletions(-) > > > > diff --git a/include/linux/gfp_types.h b/include/linux/gfp_types.h > > index 6583a58670c5..3fbe624763d9 100644 > > --- a/include/linux/gfp_types.h > > +++ b/include/linux/gfp_types.h > > @@ -21,44 +21,78 @@ typedef unsigned int __bitwise gfp_t; > > * include/trace/events/mmflags.h and tools/perf/builtin-kmem.c > > */ > > > > +enum { > > + ___GFP_DMA_BIT, > > + ___GFP_HIGHMEM_BIT, > > + ___GFP_DMA32_BIT, > > + ___GFP_MOVABLE_BIT, > > + ___GFP_RECLAIMABLE_BIT, > > + ___GFP_HIGH_BIT, > > + ___GFP_IO_BIT, > > + ___GFP_FS_BIT, > > + ___GFP_ZERO_BIT, > > + ___GFP_UNUSED_BIT, /* 0x200u unused */ > > + ___GFP_DIRECT_RECLAIM_BIT, > > + ___GFP_KSWAPD_RECLAIM_BIT, > > + ___GFP_WRITE_BIT, > > + ___GFP_NOWARN_BIT, > > + ___GFP_RETRY_MAYFAIL_BIT, > > + ___GFP_NOFAIL_BIT, > > + ___GFP_NORETRY_BIT, > > + ___GFP_MEMALLOC_BIT, > > + ___GFP_COMP_BIT, > > + ___GFP_NOMEMALLOC_BIT, > > + ___GFP_HARDWALL_BIT, > > + ___GFP_THISNODE_BIT, > > + ___GFP_ACCOUNT_BIT, > > + ___GFP_ZEROTAGS_BIT, > > +#ifdef CONFIG_KASAN_HW_TAGS > > + ___GFP_SKIP_ZERO_BIT, > > + ___GFP_SKIP_KASAN_BIT, > > +#endif > > +#ifdef CONFIG_LOCKDEP > > + ___GFP_NOLOCKDEP_BIT, > > +#endif > > + ___GFP_LAST_BIT > > +}; > > + > > /* Plain integer GFP bitmasks. Do not use this directly. */ > > -#define ___GFP_DMA 0x01u > > -#define ___GFP_HIGHMEM 0x02u > > -#define ___GFP_DMA32 0x04u > > -#define ___GFP_MOVABLE 0x08u > > -#define ___GFP_RECLAIMABLE 0x10u > > -#define ___GFP_HIGH 0x20u > > -#define ___GFP_IO 0x40u > > -#define ___GFP_FS 0x80u > > -#define ___GFP_ZERO 0x100u > > +#define ___GFP_DMA BIT(___GFP_DMA_BIT) > > +#define ___GFP_HIGHMEM BIT(___GFP_HIGHMEM_BIT) > > +#define ___GFP_DMA32 BIT(___GFP_DMA32_BIT) > > +#define ___GFP_MOVABLE BIT(___GFP_MOVABLE_BIT) > > +#define ___GFP_RECLAIMABLE BIT(___GFP_RECLAIMABLE_BIT) > > +#define ___GFP_HIGH BIT(___GFP_HIGH_BIT) > > +#define ___GFP_IO BIT(___GFP_IO_BIT) > > +#define ___GFP_FS BIT(___GFP_FS_BIT) > > +#define ___GFP_ZERO BIT(___GFP_ZERO_BIT) > > /* 0x200u unused */ > > This comment can be also removed here, because it is already stated > above with the definition of ___GFP_UNUSED_BIT. Ack. > > Then again, I think that the GFP bits have never been compacted after > Neil Brown removed __GFP_ATOMIC with commit 2973d8229b78 simply because > that would mean changing definitions of all subsequent GFP flags. FWIW > I am not aware of any code that would depend on the numeric value of > ___GFP_* macros, so this patch seems like a good opportunity to change > the numbering and get rid of this unused 0x200u altogether. > > @Neil: I have added you to the conversation in case you want to correct > my understanding of the unused bit. Hmm. I would prefer to do that in a separate patch even though it would be a one-line change. Seems safer to me in case something goes wrong and we have to bisect and revert it. If that sounds ok I'll post that in the next version. > > Other than that LGTM. Thanks for the review! Suren. > > Petr T > > > -#define ___GFP_DIRECT_RECLAIM 0x400u > > -#define ___GFP_KSWAPD_RECLAIM 0x800u > > -#define ___GFP_WRITE 0x1000u > > -#define ___GFP_NOWARN 0x2000u > > -#define ___GFP_RETRY_MAYFAIL 0x4000u > > -#define ___GFP_NOFAIL 0x8000u > > -#define ___GFP_NORETRY 0x10000u > > -#define ___GFP_MEMALLOC 0x20000u > > -#define ___GFP_COMP 0x40000u > > -#define ___GFP_NOMEMALLOC 0x80000u > > -#define ___GFP_HARDWALL 0x100000u > > -#define ___GFP_THISNODE 0x200000u > > -#define ___GFP_ACCOUNT 0x400000u > > -#define ___GFP_ZEROTAGS 0x800000u > > +#define ___GFP_DIRECT_RECLAIM BIT(___GFP_DIRECT_RECLAIM_BIT) > > +#define ___GFP_KSWAPD_RECLAIM BIT(___GFP_KSWAPD_RECLAIM_BIT) > > +#define ___GFP_WRITE BIT(___GFP_WRITE_BIT) > > +#define ___GFP_NOWARN BIT(___GFP_NOWARN_BIT) > > +#define ___GFP_RETRY_MAYFAIL BIT(___GFP_RETRY_MAYFAIL_BIT) > > +#define ___GFP_NOFAIL BIT(___GFP_NOFAIL_BIT) > > +#define ___GFP_NORETRY BIT(___GFP_NORETRY_BIT) > > +#define ___GFP_MEMALLOC BIT(___GFP_MEMALLOC_BIT) > > +#define ___GFP_COMP BIT(___GFP_COMP_BIT) > > +#define ___GFP_NOMEMALLOC BIT(___GFP_NOMEMALLOC_BIT) > > +#define ___GFP_HARDWALL BIT(___GFP_HARDWALL_BIT) > > +#define ___GFP_THISNODE BIT(___GFP_THISNODE_BIT) > > +#define ___GFP_ACCOUNT BIT(___GFP_ACCOUNT_BIT) > > +#define ___GFP_ZEROTAGS BIT(___GFP_ZEROTAGS_BIT) > > #ifdef CONFIG_KASAN_HW_TAGS > > -#define ___GFP_SKIP_ZERO 0x1000000u > > -#define ___GFP_SKIP_KASAN 0x2000000u > > +#define ___GFP_SKIP_ZERO BIT(___GFP_SKIP_ZERO_BIT) > > +#define ___GFP_SKIP_KASAN BIT(___GFP_SKIP_KASAN_BIT) > > #else > > #define ___GFP_SKIP_ZERO 0 > > #define ___GFP_SKIP_KASAN 0 > > #endif > > #ifdef CONFIG_LOCKDEP > > -#define ___GFP_NOLOCKDEP 0x4000000u > > +#define ___GFP_NOLOCKDEP BIT(___GFP_NOLOCKDEP_BIT) > > #else > > #define ___GFP_NOLOCKDEP 0 > > #endif > > -/* If the above are modified, __GFP_BITS_SHIFT may need updating */ > > > > /* > > * Physical address zone modifiers (see linux/mmzone.h - low four bits= ) > > @@ -249,7 +283,7 @@ typedef unsigned int __bitwise gfp_t; > > #define __GFP_NOLOCKDEP ((__force gfp_t)___GFP_NOLOCKDEP) > > > > /* Room for N __GFP_FOO bits */ > > -#define __GFP_BITS_SHIFT (26 + IS_ENABLED(CONFIG_LOCKDEP)) > > +#define __GFP_BITS_SHIFT ___GFP_LAST_BIT > > #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1)) > > > > /** > >