From: Lance Yang <lance.yang@linux.dev>
To: usama.arif@linux.dev
Cc: akpm@linux-foundation.org, david@kernel.org, chrisl@kernel.org,
kasong@tencent.com, ljs@kernel.org, ziy@nvidia.com,
linux-mm@kvack.org, ying.huang@linux.alibaba.com,
baoquan.he@linux.dev, willy@infradead.org, youngjun.park@lge.com,
hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev,
alex@ghiti.fr, kas@kernel.org, baohua@kernel.org,
dev.jain@arm.com, baolin.wang@linux.alibaba.com,
nico.pache@linux.dev, liam@infradead.org, ryan.roberts@arm.com,
vbabka@kernel.org, lance.yang@linux.dev,
linux-kernel@vger.kernel.org, nphamcs@gmail.com,
shikemeng@huaweicloud.com, yosry@kernel.org, qi.zheng@linux.dev,
luizcap@redhat.com, kernel-team@meta.com
Subject: Re: [PATCH v8 00/30] mm: PMD-level swap entries for anonymous THPs
Date: Sun, 4 Oct 2026 11:08:44 +0800 [thread overview]
Message-ID: <20261004030844.90483-1-lance.yang@linux.dev> (raw)
In-Reply-To: <20261002095503.3585565-1-usama.arif@linux.dev>
Hey Usama,
Staring at the swap-entry bits across architectures, and RISC-V looks a
bit off in that regard ...
With Svrsw60t59b and CONFIG_MEM_SOFT_DIRTY=y, setting swap soft-dirty also
sets _PAGE_EXEC. A migration PMD then looks present ... so the fault
handler skips the migration wait :(
And yeah, this is a pre-existing bug. I've sent a separate fix for it.
https://lore.kernel.org/linux-mm/20261004030312.90163-1-lance.yang@linux.dev/
BTW, could we also add more checks to pmd_leaf_soft_dirty_tests() so we
catch this kind of issue early? Setting a swap flag shouldn't make a
non-present PMD present, IIUC.
---8<---
diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index 863111c6d4eb..80686e2baaa1 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -762,7 +762,9 @@ static void __init pmd_leaf_soft_dirty_tests(struct pgtable_debug_args *args)
WARN_ON(!pmd_is_huge(pmd));
WARN_ON(!pmd_is_valid_softleaf(pmd));
- WARN_ON(!pmd_swp_soft_dirty(pmd_swp_mksoft_dirty(pmd)));
+ pmd = pmd_swp_mksoft_dirty(pmd);
+ WARN_ON(!pmd_swp_soft_dirty(pmd));
+ WARN_ON(pmd_present(pmd));
WARN_ON(pmd_swp_soft_dirty(pmd_swp_clear_soft_dirty(pmd)));
}
#else /* !CONFIG_TRANSPARENT_HUGEPAGE */
--
[...]
Cheers, Lance
prev parent reply other threads:[~2026-10-04 3:08 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-02 9:52 Usama Arif
2026-10-02 9:52 ` [PATCH v8 01/30] mm: rename pmd_to_softleaf_folio() to pmd_softleaf_to_folio() Usama Arif
2026-10-02 9:52 ` [PATCH v8 02/30] arm64: mm: add PMD swap-exclusive helpers Usama Arif
2026-10-02 9:52 ` [PATCH v8 03/30] loongarch: " Usama Arif
2026-10-02 14:17 ` Huacai Chen
2026-10-02 9:52 ` [PATCH v8 04/30] powerpc: " Usama Arif
2026-10-05 4:55 ` LEROY Christophe
2026-10-02 9:52 ` [PATCH v8 05/30] riscv: " Usama Arif
2026-10-02 9:52 ` [PATCH v8 06/30] s390: " Usama Arif
2026-10-02 9:52 ` [PATCH v8 07/30] x86: " Usama Arif
2026-10-05 20:14 ` Zi Yan
2026-10-02 9:52 ` [PATCH v8 08/30] mm: recognize PMD swap entries in the softleaf layer Usama Arif
2026-10-02 9:52 ` [PATCH v8 09/30] mm/debug_vm_pgtable: test PMD swap-exclusive helpers Usama Arif
2026-10-02 9:52 ` [PATCH v8 10/30] mm: make PMD migration-entry splitting explicit Usama Arif
2026-10-02 9:52 ` [PATCH v8 11/30] mm: split PMD swap entries into PTE swap entries Usama Arif
2026-10-02 9:52 ` [PATCH v8 12/30] mm/swap: allow duplicating a range of " Usama Arif
2026-10-02 9:52 ` [PATCH v8 13/30] mm: handle PMD swap entries in fork path Usama Arif
2026-10-02 9:52 ` [PATCH v8 14/30] mm: zswap: reject high-order swap cache allocations backed by zswap Usama Arif
2026-10-05 20:18 ` Yosry Ahmed
2026-10-02 9:52 ` [PATCH v8 15/30] mm: swap in PMD swap entries as whole THPs during swapoff Usama Arif
2026-10-02 9:52 ` [PATCH v8 16/30] fs/proc: account PMD swap entries in smaps Usama Arif
2026-10-02 9:52 ` [PATCH v8 17/30] mm: handle soft-dirty and uffd-wp on PMD swap entries Usama Arif
2026-10-02 9:52 ` [PATCH v8 18/30] mm/hmm: fault PMD swap entries on demand Usama Arif
2026-10-02 9:52 ` [PATCH v8 19/30] mm: free PMD swap entries in zap_huge_pmd() Usama Arif
2026-10-02 9:52 ` [PATCH v8 20/30] mm/madvise: free PMD swap entries with MADV_FREE Usama Arif
2026-10-02 9:52 ` [PATCH v8 21/30] mm/madvise: skip PMD swap entries for MADV_COLD and MADV_PAGEOUT Usama Arif
2026-10-02 9:52 ` [PATCH v8 22/30] mm/madvise: keep PMD swap entries whole for MADV_GUARD_INSTALL/REMOVE Usama Arif
2026-10-02 9:52 ` [PATCH v8 23/30] mm/mincore: report PMD swap-cache residency Usama Arif
2026-10-02 9:52 ` [PATCH v8 24/30] mm/khugepaged: treat PMD swap entries as mapped THPs Usama Arif
2026-10-02 9:52 ` [PATCH v8 25/30] mm: handle PMD swap entries in MADV_WILLNEED Usama Arif
2026-10-02 9:52 ` [PATCH v8 26/30] mm: handle PMD swap entries in UFFDIO_MOVE Usama Arif
2026-10-04 8:19 ` Lance Yang
2026-10-02 9:52 ` [PATCH v8 27/30] mm: don't PTE-batch a swap-in over a hardware-poisoned subpage Usama Arif
2026-10-02 9:52 ` [PATCH v8 28/30] mm: handle PMD swap entry faults on swap-in Usama Arif
2026-10-04 10:19 ` Lance Yang
2026-10-02 9:52 ` [PATCH v8 29/30] mm: install PMD swap entries on swap-out Usama Arif
2026-10-02 9:52 ` [PATCH v8 30/30] selftests/mm: add PMD swap entry tests Usama Arif
2026-10-02 14:28 ` [PATCH v8 00/30] mm: PMD-level swap entries for anonymous THPs David Hildenbrand (Arm)
2026-10-02 15:13 ` Zi Yan
2026-10-04 12:39 ` Usama Arif
2026-10-04 3:08 ` Lance Yang [this message]
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