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Thu, 22 Oct 2026 02:17:51 +0000 X-Mizu-Trace-ID: 9562aa6cc98d7210 X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset=utf-8 X-Archived-By: Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3901.100.1.1.12\)) Subject: Re: [PATCH v2 01/20] hugetlb: Don't restore vmemmap of non-HVOed folios on bulk restore error From: Muchun Song In-Reply-To: <20261021212738.321547-1-jthoughton@google.com> Date: Thu, 22 Oct 2026 10:17:31 +0800 Cc: akpm@linux-foundation.org, catalin.marinas@arm.com, david@kernel.org, fvdl@google.com, linu.cherian@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mark.rutland@arm.com, nikos.nikoleris@arm.com, osalvador@suse.de, rientjes@google.com, ryan.roberts@arm.com, sunnanyong@huawei.com, will@kernel.org, yuzhao@google.com Content-Transfer-Encoding: quoted-printable Message-Id: <11457D37-5AF9-46C2-95BC-CAD4B22741A1@linux.dev> References: <491B482A-8177-447A-8CDB-AF83C13A5DEE@linux.dev> <20261021212738.321547-1-jthoughton@google.com> To: James Houghton X-Mailer: Apple Mail (2.3901.100.1.1.12) X-Rspamd-Queue-Id: 4F175A0006 X-Rspam-User: X-Stat-Signature: 3ahxj9cmsfqk18ka95oca6qfyyhxie7i X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam03 X-HE-Tag: 1792635474-26572 X-HE-Meta: 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 uFTQrSPX BnVR+/qXBrjWKaOd6aGV++ZMSQiNKiZsSFsWKv7c0jF9ZIE/YBEmiJK6m9Obq61bq43vw9Zmb5HAzw9JqKpzhWNVtaFjfCjK/ZHuOMAoizEsEzsNqZ1GA+K0QmXM90zF1IY88YftRX4Je82BYnQyiLbvNq+xm5uzWFOlWd0ozCYfilVhw1hz5sTkXOniMr2uoDlaie5iRwYh90St48btBFjnndd9o5Uh7hrEXIQkHX2/MsWaVjIuqlHFH/YqA2rxeXiP7MzidDei2cUwLzG+XqKnuwskRyzEmZ3yN Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 > On Oct 22, 2026, at 05:27, James Houghton = wrote: >=20 > On Wed, Oct 21, 2026 at 2:33=E2=80=AFAM Muchun Song = wrote: >>> On Oct 3, 2026, at 08:21, James Houghton = wrote: >>> diff --git a/mm/hugetlb.c b/mm/hugetlb.c >>> index a1b51251103b..4dac7ed1df57 100644 >>> --- a/mm/hugetlb.c >>> +++ b/mm/hugetlb.c >>> @@ -1613,9 +1613,14 @@ static void bulk_vmemmap_restore_error(struct = hstate *h, >>> * page is made a surplus page and removed from the = list. >>> * If are able to restore vmemmap and free one hugetlb = page, we >>> * quit processing the list to retry the bulk operation. >>> + * >>> + * Folios whose vmemmap was never optimized (e.g. = because HVO >>> + * failed when they were allocated) can be freed right = away; >>> + * remove_hugetlb_folio() has already cleared their = hugetlb flag. >>=20 >> Since you mentioned the hugetlb flag is cleared. So it's unnecessary = to clear it again. >>=20 >>> */ >>> list_for_each_entry_safe(folio, t_folio, folio_list, = lru) >>> - if (hugetlb_vmemmap_restore_folio(h, folio)) { >>> + if = (folio_test_hugetlb_vmemmap_optimized(folio) && >>> + hugetlb_vmemmap_restore_folio(h, folio)) { >>> list_del(&folio->lru); >>> spin_lock_irq(&hugetlb_lock); >>> add_hugetlb_folio(h, folio, true); >>=20 >> Something like following: >>=20 >> diff --git a/mm/hugetlb.c b/mm/hugetlb.c >> index 6a011b627986..1ab3e61f4704 100644 >> --- a/mm/hugetlb.c >> +++ b/mm/hugetlb.c >> @@ -1616,21 +1616,31 @@ static void bulk_vmemmap_restore_error(struct = hstate *h, >> * If are able to restore vmemmap and free one hugetlb = page, we >> * quit processing the list to retry the bulk = operation. >> */ >> - list_for_each_entry_safe(folio, t_folio, folio_list, = lru) >> - if (hugetlb_vmemmap_restore_folio(h, folio)) = { >> - list_del(&folio->lru); >> + list_for_each_entry_safe(folio, t_folio, folio_list, = lru) { >> + list_del(&folio->lru); >> + >> + /* >> + * remove_hugetlb_folio() already cleared the = hugetlb flag >> + * for folios whose vmemmap was not = optimized, so they can >> + * be freed without restoring vmemmap. >> + */ >> + if (folio_test_hugetlb(folio) && >> + hugetlb_vmemmap_restore_folio(h, folio)) = { >> spin_lock_irq(&hugetlb_lock); >> add_hugetlb_folio(h, folio, true); >> spin_unlock_irq(&hugetlb_lock); >> - } else { >> - list_del(&folio->lru); >> + continue; >> + } >> + >> + if (folio_test_hugetlb(folio)) { >> spin_lock_irq(&hugetlb_lock); >> __folio_clear_hugetlb(folio); >> spin_unlock_irq(&hugetlb_lock); >> - update_and_free_hugetlb_folio(h, = folio, false); >> - cond_resched(); >> - break; >> } >> + update_and_free_hugetlb_folio(h, folio, = false); >> + cond_resched(); >> + break; >> + } >> } >> } >=20 > Thanks, Muchun. :) I think it's slightly easier to read without the = second > folio_test_hugetlb(), like this: More clear, LGTM. Thanks, Muchun >=20 > list_for_each_entry_safe(folio, t_folio, folio_list, lru) { > list_del(&folio->lru); > /* > * remove_hugetlb_folio() already cleared the hugetlb = flag > * for folios whose vmemmap was not optimized, so they = can > * be freed without restoring vmemmap. > */ > if (folio_test_hugetlb(folio)) { > if (hugetlb_vmemmap_restore_folio(h, folio)) { > spin_lock_irq(&hugetlb_lock); > add_hugetlb_folio(h, folio, true); > spin_unlock_ire(&hugetlb_lock); > continue; > } > spin_lock_irq(&hugetlb_lock); > __folio_clear_hugetlb(folio); > spin_unlock_irq(&hugetlb_lock); > } > update_and_free_hugetlb_folio(h, folio, false); > cond_resched(); > break; > } >=20 > Applied this in the v3.