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Howlett" , Vlastimil Babka Subject: Re: [PATCH 08/10] mm: introduce commit_merge(), abstracting merge operation Message-ID: <20240806154116.015e329a@mordecai.tesarici.cz> In-Reply-To: <3b04eb13b499df3ebf50ae3cde9a7ed5e76237fd.1722849860.git.lorenzo.stoakes@oracle.com> References: <3b04eb13b499df3ebf50ae3cde9a7ed5e76237fd.1722849860.git.lorenzo.stoakes@oracle.com> X-Mailer: Claws Mail 4.3.0 (GTK 3.24.42; x86_64-suse-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 4B487180018 X-Stat-Signature: 1gjkoduuasgjiue76gas9ri6s4936hp4 X-Rspamd-Server: rspam09 X-Rspam-User: X-HE-Tag: 1722951682-524559 X-HE-Meta: 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 q8n57MiT Zv3O3YQnBTjDnk5PCC4vJ2qU0G1au08Tj+lnb0mpceriHtLjkmmTYz+bQI0GS/Ic1Yenz4mk8z4Tflb5WB/xfsYBzrZGi2r5Qie1xC1CGRN5Denk2IvGeAycWmQ6BmR7orxEX5ZPtvOWWbdYE54n6y3Zhuq0tzRKkVQUBXQ1lel5cskUsQCDPGWXvVgnTEeuf8CefM1JNF20fPQ9Ers/ib2TEx+2nwdOMNHsU/H8StpW4ZMy2kbj6v/gcj8YKFKX6pMRtq3b9dn+nbNwMvBKu1vsH42lHxDKAFqPQUghb7UWcYdXYD4QD6LeQ+ACRCoHbgicoK9lTWQIRXP9smRfR2GQOOEFuVRXzL6y/ X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 5 Aug 2024 13:13:55 +0100 Lorenzo Stoakes wrote: > Pull this operation into its own function and have vma_expand() call > commit_merge() instead. > > This lays the groundwork for a subsequent patch which replaces vma_merge() > with a simpler function which can share the same code. > > Signed-off-by: Lorenzo Stoakes > --- > mm/vma.c | 57 ++++++++++++++++++++++++++++++++++++++++++++------------ > 1 file changed, 45 insertions(+), 12 deletions(-) > > diff --git a/mm/vma.c b/mm/vma.c > index a404cf718f9e..b7e3c64d5d68 100644 > --- a/mm/vma.c > +++ b/mm/vma.c > @@ -564,6 +564,49 @@ void validate_mm(struct mm_struct *mm) > } > #endif /* CONFIG_DEBUG_VM_MAPLE_TREE */ > > +/* Actually perform the VMA merge operation. */ > +static int commit_merge(struct vma_merge_struct *vmg, > + struct vm_area_struct *adjust, > + struct vm_area_struct *remove, > + struct vm_area_struct *remove2, > + long adj_start, > + bool expanded) > +{ > + struct vma_prepare vp; > + > + init_multi_vma_prep(&vp, vmg->vma, adjust, remove, remove2); > + > + if (expanded) { > + vma_iter_config(vmg->vmi, vmg->start, vmg->end); > + } else { > + vma_iter_config(vmg->vmi, adjust->vm_start + adj_start, > + adjust->vm_end); > + } It's hard to follow the logic if you the "expanded" parameter is always true. I have to look at PATCH 09/10 first to see how it is expected to be used. Is there no other way? Note that this is not needed for adjust and adj_start, because they are merely moved here from vma_expand() and passed down as parameters to other functions. Petr T > + > + if (vma_iter_prealloc(vmg->vmi, vmg->vma)) > + return -ENOMEM; > + > + vma_prepare(&vp); > + vma_adjust_trans_huge(vmg->vma, vmg->start, vmg->end, adj_start); > + vma_set_range(vmg->vma, vmg->start, vmg->end, vmg->pgoff); > + > + if (expanded) > + vma_iter_store(vmg->vmi, vmg->vma); > + > + if (adj_start) { > + adjust->vm_start += adj_start; > + adjust->vm_pgoff += PHYS_PFN(adj_start); > + if (adj_start < 0) { > + WARN_ON(expanded); > + vma_iter_store(vmg->vmi, adjust); > + } > + } > + > + vma_complete(&vp, vmg->vmi, vmg->vma->vm_mm); > + > + return 0; > +} > + > /* > * vma_merge_new_vma - Attempt to merge a new VMA into address space > * > @@ -700,7 +743,6 @@ int vma_expand(struct vma_merge_struct *vmg) > bool remove_next = false; > struct vm_area_struct *vma = vmg->vma; > struct vm_area_struct *next = vmg->next; > - struct vma_prepare vp; > > vma_start_write(vma); > if (next && (vma != next) && (vmg->end == next->vm_end)) { > @@ -713,24 +755,15 @@ int vma_expand(struct vma_merge_struct *vmg) > return ret; > } > > - init_multi_vma_prep(&vp, vma, NULL, remove_next ? next : NULL, NULL); > /* Not merging but overwriting any part of next is not handled. */ > - VM_WARN_ON(next && !vp.remove && > + VM_WARN_ON(next && !remove_next && > next != vma && vmg->end > next->vm_start); > /* Only handles expanding */ > VM_WARN_ON(vma->vm_start < vmg->start || vma->vm_end > vmg->end); > > - /* Note: vma iterator must be pointing to 'start' */ > - vma_iter_config(vmg->vmi, vmg->start, vmg->end); > - if (vma_iter_prealloc(vmg->vmi, vma)) > + if (commit_merge(vmg, NULL, remove_next ? next : NULL, NULL, 0, true)) > goto nomem; > > - vma_prepare(&vp); > - vma_adjust_trans_huge(vma, vmg->start, vmg->end, 0); > - vma_set_range(vma, vmg->start, vmg->end, vmg->pgoff); > - vma_iter_store(vmg->vmi, vma); > - > - vma_complete(&vp, vmg->vmi, vma->vm_mm); > return 0; > > nomem: