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Wed, 24 Sep 2025 06:15:18 -0400 (EDT) Date: Wed, 24 Sep 2025 11:15:16 +0100 From: Kiryl Shutsemau To: David Hildenbrand Cc: Wei Yang , akpm@linux-foundation.org, lorenzo.stoakes@oracle.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, xu.xin16@zte.com.cn, chengming.zhou@linux.dev, linux-mm@kvack.org, Dan Carpenter Subject: Re: [Patch v3 1/2] mm/ksm: get mm_slot by mm_slot_entry() when slot is !NULL Message-ID: References: <20250924004854.29889-1-richard.weiyang@gmail.com> <20250924004854.29889-2-richard.weiyang@gmail.com> <27storxu4seijr5smul3xx7pofe45ittjrchii3jtwbntalsiy@2cu3wf42drwa> <1ebbfe02-1cb5-4f7a-a640-68d5d95cb99b@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 8D883C000A X-Rspamd-Server: rspam05 X-Stat-Signature: gnkqncwuu1abt637j5h7u1mnytiy7hrf X-Rspam-User: X-HE-Tag: 1758708921-528456 X-HE-Meta: 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 X0NAmJsy 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 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 Wed, Sep 24, 2025 at 12:09:03PM +0200, David Hildenbrand wrote: > > > > > mm/ksm.c | 22 ++++++++++++---------- > > > > > 1 file changed, 12 insertions(+), 10 deletions(-) > > > > > > > > > > diff --git a/mm/ksm.c b/mm/ksm.c > > > > > index 2dbe92e3dd52..c00a21800067 100644 > > > > > --- a/mm/ksm.c > > > > > +++ b/mm/ksm.c > > > > > @@ -2921,7 +2921,7 @@ int __ksm_enter(struct mm_struct *mm) > > > > > void __ksm_exit(struct mm_struct *mm) > > > > > { > > > > > - struct ksm_mm_slot *mm_slot; > > > > > + struct ksm_mm_slot *mm_slot = NULL; > > > > > struct mm_slot *slot; > > > > > int easy_to_free = 0; > > > > > @@ -2936,15 +2936,17 @@ void __ksm_exit(struct mm_struct *mm) > > > > > spin_lock(&ksm_mmlist_lock); > > > > > slot = mm_slot_lookup(mm_slots_hash, mm); > > > > > - mm_slot = mm_slot_entry(slot, struct ksm_mm_slot, slot); > > > > > - if (mm_slot && ksm_scan.mm_slot != mm_slot) { > > > > > - if (!mm_slot->rmap_list) { > > > > > - hash_del(&slot->hash); > > > > > - list_del(&slot->mm_node); > > > > > - easy_to_free = 1; > > > > > - } else { > > > > > - list_move(&slot->mm_node, > > > > > - &ksm_scan.mm_slot->slot.mm_node); > > > > > + if (slot) { > > > > > + mm_slot = mm_slot_entry(slot, struct ksm_mm_slot, slot); > > > > > + if (ksm_scan.mm_slot != mm_slot) { > > > > > + if (!mm_slot->rmap_list) { > > > > > + hash_del(&slot->hash); > > > > > + list_del(&slot->mm_node); > > > > > + easy_to_free = 1; > > > > > + } else { > > > > > + list_move(&slot->mm_node, > > > > > + &ksm_scan.mm_slot->slot.mm_node); > > > > > + } > > > > > > > > Indent level gets extreme. > > > > > > You call this extreme? :) > > > > Emphasis on "gets". :) > > :) > > I would prefer to not make it okay to call mm_slot_entry() with a NULL > pointer. Maybe invert the checks then? if (!slot) goto unlock; mm_slot = mm_slot_entry(slot, struct ksm_mm_slot, slot); if (ksm_scan.mm_slot == mm_slot) goto unlock; if (!mm_slot->rmap_list) { ... -- Kiryl Shutsemau / Kirill A. Shutemov