From: akpm@linux-foundation.org
To: almasrymina@google.com, jthoughton@google.com,
mike.kravetz@oracle.com, mm-commits@vger.kernel.org,
stable@vger.kernel.org, weixugc@google.com
Subject: + hugetlb-userfaultfd-fix-reservation-restore-on-userfaultfd-error.patch added to -mm tree
Date: Thu, 18 Nov 2021 14:04:45 -0800 [thread overview]
Message-ID: <20211118220445.nFEgf39Il%akpm@linux-foundation.org> (raw)
The patch titled
Subject: hugetlb, userfaultfd: fix reservation restore on userfaultfd error
has been added to the -mm tree. Its filename is
hugetlb-userfaultfd-fix-reservation-restore-on-userfaultfd-error.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/hugetlb-userfaultfd-fix-reservation-restore-on-userfaultfd-error.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/hugetlb-userfaultfd-fix-reservation-restore-on-userfaultfd-error.patch
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The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Mina Almasry <almasrymina@google.com>
Subject: hugetlb, userfaultfd: fix reservation restore on userfaultfd error
Currently in the is_continue case in hugetlb_mcopy_atomic_pte(), if we
bail out using "goto out_release_unlock;" in the cases where idx >= size,
or !huge_pte_none(), the code will detect that new_pagecache_page ==
false, and so call restore_reserve_on_error(). In this case I see
restore_reserve_on_error() delete the reservation, and the following call
to remove_inode_hugepages() will increment h->resv_hugepages causing a
100% reproducible leak.
We should treat the is_continue case similar to adding a page into the
pagecache and set new_pagecache_page to true, to indicate that there is no
reservation to restore on the error path, and we need not call
restore_reserve_on_error(). Rename new_pagecache_page to
page_in_pagecache to make that clear.
Link: https://lkml.kernel.org/r/20211117193825.378528-1-almasrymina@google.com
Fixes: c7b1850dfb41 ("hugetlb: don't pass page cache pages to restore_reserve_on_error")
Signed-off-by: Mina Almasry <almasrymina@google.com>
Reported-by: James Houghton <jthoughton@google.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Wei Xu <weixugc@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/hugetlb.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
--- a/mm/hugetlb.c~hugetlb-userfaultfd-fix-reservation-restore-on-userfaultfd-error
+++ a/mm/hugetlb.c
@@ -5734,13 +5734,14 @@ int hugetlb_mcopy_atomic_pte(struct mm_s
int ret = -ENOMEM;
struct page *page;
int writable;
- bool new_pagecache_page = false;
+ bool page_in_pagecache = false;
if (is_continue) {
ret = -EFAULT;
page = find_lock_page(mapping, idx);
if (!page)
goto out;
+ page_in_pagecache = true;
} else if (!*pagep) {
/* If a page already exists, then it's UFFDIO_COPY for
* a non-missing case. Return -EEXIST.
@@ -5828,7 +5829,7 @@ int hugetlb_mcopy_atomic_pte(struct mm_s
ret = huge_add_to_page_cache(page, mapping, idx);
if (ret)
goto out_release_nounlock;
- new_pagecache_page = true;
+ page_in_pagecache = true;
}
ptl = huge_pte_lockptr(h, dst_mm, dst_pte);
@@ -5892,7 +5893,7 @@ out_release_unlock:
if (vm_shared || is_continue)
unlock_page(page);
out_release_nounlock:
- if (!new_pagecache_page)
+ if (!page_in_pagecache)
restore_reserve_on_error(h, dst_vma, dst_addr, page);
put_page(page);
goto out;
_
Patches currently in -mm which might be from almasrymina@google.com are
hugetlb-userfaultfd-fix-reservation-restore-on-userfaultfd-error.patch
next reply other threads:[~2021-11-18 22:04 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-18 22:04 akpm [this message]
-- strict thread matches above, loose matches on Subject: below --
2021-11-18 22:04 + hugetlb-userfaultfd-fix-reservation-restore-on-userfaultfd-error.patch added to -mm tree akpm
2021-11-17 0:32 akpm
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