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Tue, 10 Feb 2026 22:16:18 -0800 (PST) X-Received: by 2002:a05:690c:c50b:b0:794:b5aa:9c71 with SMTP id 00721157ae682-7966aaa4a87mr12337537b3.34.1770790578186; Tue, 10 Feb 2026 22:16:18 -0800 (PST) MIME-Version: 1.0 References: <20260211031512.261127-1-senozhatsky@chromium.org> In-Reply-To: <20260211031512.261127-1-senozhatsky@chromium.org> From: Nico Pache Date: Tue, 10 Feb 2026 23:15:52 -0700 X-Gm-Features: AZwV_Qh_iVpvEC5HEA7kAQ_X-Ds2o1CqyyYvsjm4JoFkdA9yHt0YUMrrpuO2d9I Message-ID: Subject: Re: [PATCHv2] mm: khugepaged: make scan loops suspend aware To: Sergey Senozhatsky Cc: Andrew Morton , David Hildenbrand , Lorenzo Stoakes , Zi Yan , Baolin Wang , "Liam R. Howlett" , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , linux-mm@kvack.org, linux-kernel@vger.kernel.org X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: s7sBp-70_h2O1QvRic5j1eLTzQts7kEzmDLPvXbxPtU_1770790578 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Queue-Id: 2E487160005 X-Rspamd-Server: rspam07 X-Stat-Signature: m6y4o7fqcpsxp7iw8km4yex8m5ythey8 X-HE-Tag: 1770790581-261536 X-HE-Meta: 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 64USdS3H P+PGoC3OBpyHRUDRYw42gk8SoAWMOpFWtrHV4QwEtdzfWC0g+aOuRIKiXr2veBdxzKvI5Te3qv27EuhBB7jowATiVbpu7T++MmO2Y6JOskMZ7SzKJaV7ZpgE0IJvlYMFiUUEwO+k/0JDV/oti7pMHl0sZq8UgsmiFAnUA4YG84SViJxWx81+RrzZUpGE9zo8Vwvhkq0td0YTsZbY7SljSfJ//deNgo0wYy7lMQcSsxMpe4G1n16+rkjNH7NrUK+jRKMS/W4CI8fnXLcXj1SgbceAQ6UxaJdzwd0wAbqxNNr2O+PQhcI90ecExRQUUysCt3fEDVEh1V42hM4Eihw1EExFTMGwF+RMoRgGg 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 Tue, Feb 10, 2026 at 8:15=E2=80=AFPM Sergey Senozhatsky wrote: > > A number of khugepaaged's loops, e.g. khugepaged_scan_mm_slot(), > are time unbound, which can become problematic during system > suspend: > > PM: suspend entry (s2idle) > Filesystems sync: 0.003 seconds > Freezing user space processes > Freezing user space processes completed (elapsed 0.003 seconds) > OOM killer disabled. > Freezing remaining freezable tasks > Freezing remaining freezable tasks failed after 20.004 seconds (1 tasks r= efusing to freeze, wq_busy=3D0): > task:khugepaged state:D stack:0 pid:1345 ppid:2 flags:0x00= 004000 > Call Trace: > > schedule+0x523/0x16a0 > schedule_timeout+0x23b/0x6e0 > io_schedule_timeout+0x3f/0x80 > wait_for_completion_io_timeout+0xe4/0x170 > submit_bio_wait+0x79/0xc0 > swap_readpage+0x150/0x2d0 > swap_cluster_readahead+0x3be/0x750 > shmem_swapin+0xa7/0x100 > shmem_swapin_folio+0xcd/0x2e0 > shmem_get_folio+0x237/0x580 > collapse_file+0x247/0x1280 > hpage_collapse_scan_file+0x26e/0x380 > khugepaged+0x43b/0x810 > kthread+0xfb/0x120 > > > Make hpage_collapse_test_exit_or_disable() suspend aware so > that khugepaaged's scan loops can terminate in a timely manner > and let system enter the sleep state. > > Co-developed-by: Baolin Wang > Signed-off-by: Sergey Senozhatsky Hi Sergey! Thank you for reporting this and taking the time to investigate a fix. Here are some simple review points then I'll comment on the code below. - We usually send "To:" the mailing lists and "CC:" to all other people. - Your subject contains "PATCHv2" there should be a space there - It would be worth noting the "HOW" in the commit message > --- > > v1->v2: Actually pass "cc" to hpage_collapse_test_exit_or_disable() > > mm/khugepaged.c | 22 +++++++++++++++------- > 1 file changed, 15 insertions(+), 7 deletions(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index eff9e3061925..d32a5ad27097 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -392,10 +392,18 @@ static inline int hpage_collapse_test_exit(struct m= m_struct *mm) > return atomic_read(&mm->mm_users) =3D=3D 0; > } > > -static inline int hpage_collapse_test_exit_or_disable(struct mm_struct *= mm) > +static inline int hpage_collapse_test_exit_or_disable(struct mm_struct *= mm, > + struct collapse_control *= cc) > { > + bool was_frozen =3D false; > + > + if (cc->is_khugepaged && > + unlikely(kthread_freezable_should_stop(&was_frozen))) > + return 1; > + > return hpage_collapse_test_exit(mm) || > - mm_flags_test(MMF_DISABLE_THP_COMPLETELY, mm); > + mm_flags_test(MMF_DISABLE_THP_COMPLETELY, mm) || > + was_frozen; I dont really understand the freezer code, and there are few examples of this. But given how other callers do it, this seems correct. > } > > static bool hugepage_pmd_enabled(void) > @@ -895,7 +903,7 @@ static enum scan_result hugepage_vma_revalidate(struc= t mm_struct *mm, unsigned l > enum tva_type type =3D cc->is_khugepaged ? TVA_KHUGEPAGED : > TVA_FORCED_COLLAPSE; > > - if (unlikely(hpage_collapse_test_exit_or_disable(mm))) > + if (unlikely(hpage_collapse_test_exit_or_disable(mm, cc))) > return SCAN_ANY_PROCESS; > > *vmap =3D vma =3D find_vma(mm, address); > @@ -2420,7 +2428,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigne= d int pages, enum scan_result > goto breakouterloop_mmap_lock; > > progress++; > - if (unlikely(hpage_collapse_test_exit_or_disable(mm))) > + if (unlikely(hpage_collapse_test_exit_or_disable(mm, cc))) > goto breakouterloop; > > vma_iter_init(&vmi, mm, khugepaged_scan.address); > @@ -2428,7 +2436,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigne= d int pages, enum scan_result > unsigned long hstart, hend; > > cond_resched(); > - if (unlikely(hpage_collapse_test_exit_or_disable(mm))) { > + if (unlikely(hpage_collapse_test_exit_or_disable(mm, cc))= ) { > progress++; > break; > } > @@ -2450,7 +2458,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigne= d int pages, enum scan_result > bool mmap_locked =3D true; > > cond_resched(); > - if (unlikely(hpage_collapse_test_exit_or_disable(= mm))) > + if (unlikely(hpage_collapse_test_exit_or_disable(= mm, cc))) > goto breakouterloop; > > VM_BUG_ON(khugepaged_scan.address < hstart || > @@ -2468,7 +2476,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigne= d int pages, enum scan_result > fput(file); > if (*result =3D=3D SCAN_PTE_MAPPED_HUGEPA= GE) { > mmap_read_lock(mm); > - if (hpage_collapse_test_exit_or_d= isable(mm)) > + if (hpage_collapse_test_exit_or_d= isable(mm, cc)) > goto breakouterloop; > *result =3D try_collapse_pte_mapp= ed_thp(mm, > khugepaged_scan.address, = false); > -- > 2.53.0.239.g8d8fc8a987-goog >