From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Hugh Dickins <hughd@google.com>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: [PATCH 4.14 25/30] mm: thp: fix MADV_REMOVE deadlock on shmem THP
Date: Mon, 8 Feb 2021 16:01:11 +0100 [thread overview]
Message-ID: <20210208145806.261891437@linuxfoundation.org> (raw)
In-Reply-To: <20210208145805.239714726@linuxfoundation.org>
From: Hugh Dickins <hughd@google.com>
commit 1c2f67308af4c102b4e1e6cd6f69819ae59408e0 upstream.
Sergey reported deadlock between kswapd correctly doing its usual
lock_page(page) followed by down_read(page->mapping->i_mmap_rwsem), and
madvise(MADV_REMOVE) on an madvise(MADV_HUGEPAGE) area doing
down_write(page->mapping->i_mmap_rwsem) followed by lock_page(page).
This happened when shmem_fallocate(punch hole)'s unmap_mapping_range()
reaches zap_pmd_range()'s call to __split_huge_pmd(). The same deadlock
could occur when partially truncating a mapped huge tmpfs file, or using
fallocate(FALLOC_FL_PUNCH_HOLE) on it.
__split_huge_pmd()'s page lock was added in 5.8, to make sure that any
concurrent use of reuse_swap_page() (holding page lock) could not catch
the anon THP's mapcounts and swapcounts while they were being split.
Fortunately, reuse_swap_page() is never applied to a shmem or file THP
(not even by khugepaged, which checks PageSwapCache before calling), and
anonymous THPs are never created in shmem or file areas: so that
__split_huge_pmd()'s page lock can only be necessary for anonymous THPs,
on which there is no risk of deadlock with i_mmap_rwsem.
Link: https://lkml.kernel.org/r/alpine.LSU.2.11.2101161409470.2022@eggly.anvils
Fixes: c444eb564fb1 ("mm: thp: make the THP mapcount atomic against __split_huge_pmd_locked()")
Signed-off-by: Hugh Dickins <hughd@google.com>
Reported-by: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
mm/huge_memory.c | 37 +++++++++++++++++++++++--------------
1 file changed, 23 insertions(+), 14 deletions(-)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2198,7 +2198,7 @@ void __split_huge_pmd(struct vm_area_str
spinlock_t *ptl;
struct mm_struct *mm = vma->vm_mm;
unsigned long haddr = address & HPAGE_PMD_MASK;
- bool was_locked = false;
+ bool do_unlock_page = false;
pmd_t _pmd;
mmu_notifier_invalidate_range_start(mm, haddr, haddr + HPAGE_PMD_SIZE);
@@ -2211,7 +2211,6 @@ void __split_huge_pmd(struct vm_area_str
VM_BUG_ON(freeze && !page);
if (page) {
VM_WARN_ON_ONCE(!PageLocked(page));
- was_locked = true;
if (page != pmd_page(*pmd))
goto out;
}
@@ -2220,19 +2219,29 @@ repeat:
if (pmd_trans_huge(*pmd)) {
if (!page) {
page = pmd_page(*pmd);
- if (unlikely(!trylock_page(page))) {
- get_page(page);
- _pmd = *pmd;
- spin_unlock(ptl);
- lock_page(page);
- spin_lock(ptl);
- if (unlikely(!pmd_same(*pmd, _pmd))) {
- unlock_page(page);
+ /*
+ * An anonymous page must be locked, to ensure that a
+ * concurrent reuse_swap_page() sees stable mapcount;
+ * but reuse_swap_page() is not used on shmem or file,
+ * and page lock must not be taken when zap_pmd_range()
+ * calls __split_huge_pmd() while i_mmap_lock is held.
+ */
+ if (PageAnon(page)) {
+ if (unlikely(!trylock_page(page))) {
+ get_page(page);
+ _pmd = *pmd;
+ spin_unlock(ptl);
+ lock_page(page);
+ spin_lock(ptl);
+ if (unlikely(!pmd_same(*pmd, _pmd))) {
+ unlock_page(page);
+ put_page(page);
+ page = NULL;
+ goto repeat;
+ }
put_page(page);
- page = NULL;
- goto repeat;
}
- put_page(page);
+ do_unlock_page = true;
}
}
if (PageMlocked(page))
@@ -2242,7 +2251,7 @@ repeat:
__split_huge_pmd_locked(vma, pmd, haddr, freeze);
out:
spin_unlock(ptl);
- if (!was_locked && page)
+ if (do_unlock_page)
unlock_page(page);
mmu_notifier_invalidate_range_end(mm, haddr, haddr + HPAGE_PMD_SIZE);
}
next prev parent reply other threads:[~2021-02-08 16:26 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-08 15:00 [PATCH 4.14 00/30] 4.14.221-rc1 review Greg Kroah-Hartman
2021-02-08 15:00 ` [PATCH 4.14 01/30] USB: serial: cp210x: add pid/vid for WSDA-200-USB Greg Kroah-Hartman
2021-02-08 15:00 ` [PATCH 4.14 02/30] USB: serial: cp210x: add new VID/PID for supporting Teraoka AD2000 Greg Kroah-Hartman
2021-02-08 15:00 ` [PATCH 4.14 03/30] USB: serial: option: Adding support for Cinterion MV31 Greg Kroah-Hartman
2021-02-08 15:00 ` [PATCH 4.14 04/30] Input: i8042 - unbreak Pegatron C15B Greg Kroah-Hartman
2021-02-08 15:00 ` [PATCH 4.14 05/30] arm64: dts: ls1046a: fix dcfg address range Greg Kroah-Hartman
2021-02-08 15:00 ` [PATCH 4.14 06/30] net: lapb: Copy the skb before sending a packet Greg Kroah-Hartman
2021-02-08 15:00 ` [PATCH 4.14 07/30] objtool: Support Clang non-section symbols in ORC generation Greg Kroah-Hartman
2021-02-08 15:00 ` [PATCH 4.14 08/30] elfcore: fix building with clang Greg Kroah-Hartman
2021-02-08 15:00 ` [PATCH 4.14 09/30] ipv4: fix race condition between route lookup and invalidation Greg Kroah-Hartman
2021-02-08 15:00 ` [PATCH 4.14 10/30] USB: gadget: legacy: fix an error code in eth_bind() Greg Kroah-Hartman
2021-02-08 15:00 ` [PATCH 4.14 11/30] USB: usblp: dont call usb_set_interface if theres a single alt Greg Kroah-Hartman
2021-02-08 15:00 ` [PATCH 4.14 12/30] usb: dwc2: Fix endpoint direction check in ep_from_windex Greg Kroah-Hartman
2021-02-08 15:00 ` [PATCH 4.14 13/30] ovl: fix dentry leak in ovl_get_redirect Greg Kroah-Hartman
2021-02-08 15:01 ` [PATCH 4.14 14/30] mac80211: fix station rate table updates on assoc Greg Kroah-Hartman
2021-02-08 15:01 ` [PATCH 4.14 15/30] kretprobe: Avoid re-registration of the same kretprobe earlier Greg Kroah-Hartman
2021-02-08 15:01 ` [PATCH 4.14 16/30] xhci: fix bounce buffer usage for non-sg list case Greg Kroah-Hartman
2021-02-08 15:01 ` [PATCH 4.14 17/30] cifs: report error instead of invalid when revalidating a dentry fails Greg Kroah-Hartman
2021-02-08 15:01 ` [PATCH 4.14 18/30] smb3: Fix out-of-bounds bug in SMB2_negotiate() Greg Kroah-Hartman
2021-02-08 15:01 ` [PATCH 4.14 19/30] mmc: core: Limit retries when analyse of SDIO tuples fails Greg Kroah-Hartman
2021-02-08 15:01 ` [PATCH 4.14 20/30] nvme-pci: avoid the deepest sleep state on Kingston A2000 SSDs Greg Kroah-Hartman
2021-02-08 15:01 ` [PATCH 4.14 21/30] ARM: footbridge: fix dc21285 PCI configuration accessors Greg Kroah-Hartman
2021-02-08 15:01 ` [PATCH 4.14 22/30] mm: hugetlbfs: fix cannot migrate the fallocated HugeTLB page Greg Kroah-Hartman
2021-02-08 15:01 ` [PATCH 4.14 23/30] mm: hugetlb: fix a race between isolating and freeing page Greg Kroah-Hartman
2021-02-08 15:01 ` [PATCH 4.14 24/30] mm: hugetlb: remove VM_BUG_ON_PAGE from page_huge_active Greg Kroah-Hartman
2021-02-08 15:01 ` Greg Kroah-Hartman [this message]
2021-02-08 15:01 ` [PATCH 4.14 26/30] x86/build: Disable CET instrumentation in the kernel Greg Kroah-Hartman
2021-02-08 15:01 ` [PATCH 4.14 27/30] x86/apic: Add extra serialization for non-serializing MSRs Greg Kroah-Hartman
2021-02-08 15:01 ` [PATCH 4.14 28/30] Input: xpad - sync supported devices with fork on GitHub Greg Kroah-Hartman
2021-02-08 15:01 ` [PATCH 4.14 29/30] iommu/vt-d: Do not use flush-queue when caching-mode is on Greg Kroah-Hartman
2021-02-08 15:01 ` [PATCH 4.14 30/30] net: dsa: mv88e6xxx: override existent unicast portvec in port_fdb_add Greg Kroah-Hartman
2021-02-09 17:34 ` [PATCH 4.14 00/30] 4.14.221-rc1 review Naresh Kamboju
2021-02-09 18:10 ` Guenter Roeck
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