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[172.10.233.147]) by smtp.gmail.com with ESMTPSA id j185-20020a816ec2000000b00592236855cesm2259304ywc.61.2023.09.25.01.30.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Sep 2023 01:30:53 -0700 (PDT) Date: Mon, 25 Sep 2023 01:30:51 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@ripple.attlocal.net To: Andrew Morton cc: Andi Kleen , Christoph Lameter , Matthew Wilcox , Mike Kravetz , David Hildenbrand , Suren Baghdasaryan , Yang Shi , Sidhartha Kumar , Vishal Moola , Kefeng Wang , Greg Kroah-Hartman , Tejun Heo , Mel Gorman , Michal Hocko , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 08/12] mempolicy: remove confusing MPOL_MF_LAZY dead code In-Reply-To: <2d872cef-7787-a7ca-10e-9d45a64c80b4@google.com> Message-ID: <2cb8b08a-a96c-2a61-94dd-4cd51ad0605d@google.com> References: <2d872cef-7787-a7ca-10e-9d45a64c80b4@google.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" v3.8 commit b24f53a0bea3 ("mm: mempolicy: Add MPOL_MF_LAZY") introduced MPOL_MF_LAZY, and included it in the MPOL_MF_VALID flags; but a720094ded8 ("mm: mempolicy: Hide MPOL_NOOP and MPOL_MF_LAZY from userspace for now") immediately removed it from MPOL_MF_VALID flags, pending further review. "This will need to be revisited", but it has not been reinstated. The present state is confusing: there is dead code in mm/mempolicy.c to handle MPOL_MF_LAZY cases which can never occur. Remove that: it can be resurrected later if necessary. But keep the definition of MPOL_MF_LAZY, which must remain in the UAPI, even though it always fails with EINVAL. https://lore.kernel.org/linux-mm/1553041659-46787-1-git-send-email-yang.shi= @linux.alibaba.com/ links to a previous request to remove MPOL_MF_LAZY. Signed-off-by: Hugh Dickins Reviewed-by: Matthew Wilcox (Oracle) --- include/uapi/linux/mempolicy.h | 2 +- mm/mempolicy.c | 18 ------------------ 2 files changed, 1 insertion(+), 19 deletions(-) diff --git a/include/uapi/linux/mempolicy.h b/include/uapi/linux/mempolicy.h index 046d0ccba4cd..a8963f7ef4c2 100644 --- a/include/uapi/linux/mempolicy.h +++ b/include/uapi/linux/mempolicy.h @@ -48,7 +48,7 @@ enum { #define MPOL_MF_MOVE (1<<1) /* Move pages owned by this process to conform to policy */ #define MPOL_MF_MOVE_ALL (1<<2) /* Move every page to conform to policy */ -#define MPOL_MF_LAZY (1<<3) /* Modifies '_MOVE: lazy migrate on fault */ +#define MPOL_MF_LAZY (1<<3) /* UNSUPPORTED FLAG: Lazy migrate on fault */ #define MPOL_MF_INTERNAL (1<<4) /* Internal flags start here */ =20 #define MPOL_MF_VALID (MPOL_MF_STRICT | \ diff --git a/mm/mempolicy.c b/mm/mempolicy.c index a22b641cfd6b..7ab6102d7da4 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -632,12 +632,6 @@ unsigned long change_prot_numa(struct vm_area_struct *= vma, =20 return nr_updated; } -#else -static unsigned long change_prot_numa(struct vm_area_struct *vma, - unsigned long addr, unsigned long end) -{ - return 0; -} #endif /* CONFIG_NUMA_BALANCING */ =20 static int queue_pages_test_walk(unsigned long start, unsigned long end, @@ -676,14 +670,6 @@ static int queue_pages_test_walk(unsigned long start, = unsigned long end, if (endvma > end) endvma =3D end; =20 - if (flags & MPOL_MF_LAZY) { - /* Similar to task_numa_work, skip inaccessible VMAs */ - if (!is_vm_hugetlb_page(vma) && vma_is_accessible(vma) && - !(vma->vm_flags & VM_MIXEDMAP)) - change_prot_numa(vma, start, endvma); - return 1; - } - /* * Check page nodes, and queue pages to move, in the current vma. * But if no moving, and no strict checking, the scan can be skipped. @@ -1271,9 +1257,6 @@ static long do_mbind(unsigned long start, unsigned lo= ng len, if (IS_ERR(new)) return PTR_ERR(new); =20 - if (flags & MPOL_MF_LAZY) - new->flags |=3D MPOL_F_MOF; - /* * If we are using the default policy then operation * on discontinuous address spaces is okay after all @@ -1318,7 +1301,6 @@ static long do_mbind(unsigned long start, unsigned lo= ng len, =20 if (!err) { if (!list_empty(&pagelist)) { - WARN_ON_ONCE(flags & MPOL_MF_LAZY); nr_failed |=3D migrate_pages(&pagelist, new_folio, NULL, start, MIGRATE_SYNC, MR_MEMPOLICY_MBIND, NULL); } --=20 2.35.3