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bh=OadfzCGW2WfZe3bKn2zs0QyfwtQX+wSf4CH5BaN2Vtw=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1794455266; v=1; x=1795060066; b=Pg/fy7SQkfATu7EVEkhbXVw4DwKfwKMto0NUPELfZ9AHXXR8xaAOlByyv+FN8K5l/dRzXkQL dfPCAwb6k9VOG0jSKXgv9YohjOi17WCLOY5hLDqrkMYDhboVmWszad9rSC+0FKMqOKXguOaensd 9MhvQArqYWMf97YkIr4S4FRo= X-Envelope-To: linux-kernel@vger.kernel.org Received: by mta12.migadu.com with ESMTPS id 64ab2262467329c6; Thu, 12 Nov 2026 03:47:45 +0000 X-Mizu-Trace-ID: 64ab2262467329c6 X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset=utf-8 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3901.200.71.1.16\)) 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: <11457D37-5AF9-46C2-95BC-CAD4B22741A1@linux.dev> Date: Thu, 12 Nov 2026 11:47:28 +0800 Cc: akpm@linux-foundation.org, catalin.marinas@arm.com, David Hildenbrand , 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: References: <491B482A-8177-447A-8CDB-AF83C13A5DEE@linux.dev> <20261021212738.321547-1-jthoughton@google.com> <11457D37-5AF9-46C2-95BC-CAD4B22741A1@linux.dev> To: James Houghton X-Mailer: Apple Mail (2.3901.200.71.1.16) > On Oct 22, 2026, at 10:17, Muchun Song wrote: >=20 >=20 >=20 >> 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: Hi James, Could you send it as a separate fix patch so that we could merge it = first? Thanks. >=20 > More clear, LGTM. >=20 > Thanks, > Muchun