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freedreno@lists.freedesktop.org, linux-tegra@vger.kernel.org, kvm@vger.kernel.org, Russell King Subject: Re: [PATCH v2 13/33] mm/vma: introduce and use vmg_pages(), vmg_[start, end]_pgoff() Message-ID: References: <20260710-b4-pre-scalable-cow-v2-0-2a5aa403d977@kernel.org> <20260710-b4-pre-scalable-cow-v2-13-2a5aa403d977@kernel.org> <508301c5-5460-40e8-bc34-6410be5be40a@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <508301c5-5460-40e8-bc34-6410be5be40a@kernel.org> X-Rspamd-Queue-Id: 3F68640005 X-Rspam-User: X-Stat-Signature: gmyzeiprgry3yh9dpdb5ich8z61fn165 X-Rspamd-Server: rspam03 X-HE-Tag: 1784024268-60052 X-HE-Meta: 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Vhr9O8+t3gZF/ijrLduku30Wxn/afHGjcBZ6z2PVQt4AqNCScycpB852NRUhh35fWhIW+ZxVqZbNhN87ZGPQug/wr37181Pjz5+Ld1JECyJzeZP8cic4Ub6XyhGKF6QUuVkP0OnQR/Y0j/LJ5C+vWTgNLXdp1ofz5gH1HTIdnHz6tc7BGkJUQlh9j/lAB7hWLn4FGn6xBU8Nme7SiuZbrUhrKlu8ZG7PFVaaCfp4bvgxFYXV5F4or6ZqMr92mfhIkGGQ9m12e0ZLBx6vLOU9NlvlG+V1WT4P/xAH5SndDSl/sChUnncZqLsvrBk7EuRePmsJuePPcJjYsGzYrIktWoR3d1gLAcAEPkYwNeiQ3yJf7Cm1pgnw0hTLPac9KkzVasgDstMh8cyISvJTMcz9OeqDx2FD8O96r3Wk0QqRxcXr5wZHKSZKxJJ3aqKrA27mlZ2w8SKKbFNoCR1bbKidlXsPeSDa0cuYGVayQYvRRAE5l7Ekx4aWIldQB5v5fV/d3230GwJjFv60kZDWssPvq+uOzbdbhH+t2XtMkAL7xE1YulA8h1w+hlpY2D/PPe+JHPyVTBI6Gn0vMaSEoOkmlD Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jul 13, 2026 at 08:12:24PM +0200, Vlastimil Babka (SUSE) wrote: > On 7/10/26 22:16, Lorenzo Stoakes wrote: > > In the VMA logic we often need to determine the number of pages in the > > specified merge range, as well as the start and end page offsets of that > > range. > > > > Introduce and use helpers for these purposes. > > > > No functional change intended. > > > > Reviewed-by: Pedro Falcato > > Reviewed-by: Gregory Price > > Signed-off-by: Lorenzo Stoakes > > Uh, the PHYS_PFN() usage here was quite an abuse. Good riddance. Yeah and mine :)) but absolutely agree it was wrong and glad to fix my own mistake in using that ;) > Reviewed-by: Vlastimil Babka (SUSE) Thanks! > > > --- > > mm/vma.c | 11 ++++------- > > mm/vma.h | 17 +++++++++++++++++ > > 2 files changed, 21 insertions(+), 7 deletions(-) > > > > diff --git a/mm/vma.c b/mm/vma.c > > index 35ba3475128f..995de8198fbb 100644 > > --- a/mm/vma.c > > +++ b/mm/vma.c > > @@ -197,11 +197,9 @@ static void init_multi_vma_prep(struct vma_prepare *vp, > > */ > > static bool can_vma_merge_before(struct vma_merge_struct *vmg) > > { > > - pgoff_t pglen = PHYS_PFN(vmg->end - vmg->start); > > - > > if (is_mergeable_vma(vmg, /* merge_next = */ true) && > > is_mergeable_anon_vma(vmg, /* merge_next = */ true)) { > > - if (vmg->next->vm_pgoff == vmg->pgoff + pglen) > > + if (vmg_end_pgoff(vmg) == vma_start_pgoff(vmg->next)) > > return true; > > } > > > > @@ -221,7 +219,7 @@ static bool can_vma_merge_after(struct vma_merge_struct *vmg) > > { > > if (is_mergeable_vma(vmg, /* merge_next = */ false) && > > is_mergeable_anon_vma(vmg, /* merge_next = */ false)) { > > - if (vmg->prev->vm_pgoff + vma_pages(vmg->prev) == vmg->pgoff) > > + if (vma_end_pgoff(vmg->prev) == vmg_start_pgoff(vmg)) > > return true; > > } > > return false; > > @@ -759,7 +757,7 @@ static int commit_merge(struct vma_merge_struct *vmg) > > */ > > vma_adjust_trans_huge(vma, vmg->start, vmg->end, > > vmg->__adjust_middle_start ? vmg->middle : NULL); > > - vma_set_range(vma, vmg->start, vmg->end, vmg->pgoff); > > + vma_set_range(vma, vmg->start, vmg->end, vmg_start_pgoff(vmg)); > > vmg_adjust_set_range(vmg); > > vma_iter_store_overwrite(vmg->vmi, vmg->target); > > > > @@ -962,8 +960,7 @@ static __must_check struct vm_area_struct *vma_merge_existing_range( > > * middle next > > * shrink/delete extend > > */ > > - > > - pgoff_t pglen = PHYS_PFN(vmg->end - vmg->start); > > + const pgoff_t pglen = vmg_pages(vmg); > > > > VM_WARN_ON_VMG(!merge_right, vmg); > > /* If we are offset into a VMA, then prev must be middle. */ > > diff --git a/mm/vma.h b/mm/vma.h > > index 8e4b61a7304c..527716c8739d 100644 > > --- a/mm/vma.h > > +++ b/mm/vma.h > > @@ -230,6 +230,23 @@ static inline bool vmg_nomem(struct vma_merge_struct *vmg) > > return vmg->state == VMA_MERGE_ERROR_NOMEM; > > } > > > > +static inline pgoff_t vmg_start_pgoff(const struct vma_merge_struct *vmg) > > +{ > > + return vmg->pgoff; > > +} > > + > > +static inline pgoff_t vmg_pages(const struct vma_merge_struct *vmg) > > +{ > > + const unsigned long size = vmg->end - vmg->start; > > + > > + return size >> PAGE_SHIFT; > > +} > > + > > +static inline pgoff_t vmg_end_pgoff(const struct vma_merge_struct *vmg) > > +{ > > + return vmg_start_pgoff(vmg) + vmg_pages(vmg); > > +} > > + > > /* Assumes addr >= vma->vm_start. */ > > static inline pgoff_t vma_pgoff_offset(struct vm_area_struct *vma, > > unsigned long addr) > > > Cheers, Lorenzo