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Groups > linux.kernel > #1551415
| From | Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 4.4 21/60] Btrfs: fix memory leak in reading btree blocks |
| Date | 2017-01-04 22:40 +0100 |
| Message-ID | <sW1rQ-1SX-41@gated-at.bofh.it> (permalink) |
| References | <sW0Fr-1jk-5@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Liu Bo <bo.li.liu@oracle.com>
commit 2571e739677f1e4c0c63f5ed49adcc0857923625 upstream.
So we can read a btree block via readahead or intentional read,
and we can end up with a memory leak when something happens as
follows,
1) readahead starts to read block A but does not wait for read
completion,
2) btree_readpage_end_io_hook finds that block A is corrupted,
and it needs to clear all block A's pages' uptodate bit.
3) meanwhile an intentional read kicks in and checks block A's
pages' uptodate to decide which page needs to be read.
4) when some pages have the uptodate bit during 3)'s check so
3) doesn't count them for eb->io_pages, but they are later
cleared by 2) so we has to readpage on the page, we get
the wrong eb->io_pages which results in a memory leak of
this block.
This fixes the problem by firstly getting all pages's locking and
then checking pages' uptodate bit.
t1(readahead) t2(readahead endio) t3(the following read)
read_extent_buffer_pages end_bio_extent_readpage
for pg in eb: for page 0,1,2 in eb:
if pg is uptodate: btree_readpage_end_io_hook(pg)
num_reads++ if uptodate:
eb->io_pages = num_reads SetPageUptodate(pg) _______________
for pg in eb: for page 3 in eb: read_extent_buffer_pages
if pg is NOT uptodate: btree_readpage_end_io_hook(pg) for pg in eb:
__extent_read_full_page(pg) sanity check reports something wrong if pg is uptodate:
clear_extent_buffer_uptodate(eb) num_reads++
for pg in eb: eb->io_pages = num_reads
ClearPageUptodate(page) _______________
for pg in eb:
if pg is NOT uptodate:
__extent_read_full_page(pg)
So t3's eb->io_pages is not consistent with the number of pages it's reading,
and during endio(), atomic_dec_and_test(&eb->io_pages) will get a negative
number so that we're not able to free the eb.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/btrfs/extent_io.c | 9 +++++++++
1 file changed, 9 insertions(+)
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -5294,11 +5294,20 @@ int read_extent_buffer_pages(struct exte
lock_page(page);
}
locked_pages++;
+ }
+ /*
+ * We need to firstly lock all pages to make sure that
+ * the uptodate bit of our pages won't be affected by
+ * clear_extent_buffer_uptodate().
+ */
+ for (i = start_i; i < num_pages; i++) {
+ page = eb->pages[i];
if (!PageUptodate(page)) {
num_reads++;
all_uptodate = 0;
}
}
+
if (all_uptodate) {
if (start_i == 0)
set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
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[PATCH 4.4 00/60] 4.4.40-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 22:30 +0100
[PATCH 4.4 47/60] dm flakey: return -EINVAL on interval bounds error in flakey_ctr() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 22:30 +0100
[PATCH 4.4 07/60] USB: serial: kl5kusb105: fix open error path Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 22:40 +0100
[PATCH 4.4 34/60] ext4: use more strict checks for inodes_per_block on mount Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 22:40 +0100
[PATCH 4.4 33/60] ext4: fix stack memory corruption with 64k block size Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 22:40 +0100
[PATCH 4.4 36/60] ext4: add sanity checking to count_overhead() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 22:40 +0100
[PATCH 4.4 30/60] ptrace: Capture the ptracers creds not PT_PTRACE_CAP Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 22:40 +0100
[PATCH 4.4 18/60] ALSA: hda - Gate the mic jack on HP Z1 Gen3 AiO Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 22:40 +0100
[PATCH 4.4 03/60] btrfs: store and load values of stripes_min/stripes_max in balance status item Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 22:40 +0100
[PATCH 4.4 21/60] Btrfs: fix memory leak in reading btree blocks Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 22:40 +0100
[PATCH 4.4 06/60] USB: serial: option: add dlink dwm-158 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 22:40 +0100
[PATCH 4.4 05/60] USB: serial: option: add support for Telit LE922A PIDs 0x1040, 0x1041 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 22:40 +0100
[PATCH 4.4 08/60] USB: cdc-acm: add device id for GW Instek AFG-125 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 22:40 +0100
[PATCH 4.4 32/60] ext4: fix mballoc breakage with 64k block size Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 22:40 +0100
[PATCH 4.4 04/60] Btrfs: fix qgroup rescan worker initialization Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 22:40 +0100
[PATCH 4.4 09/60] usb: hub: Fix auto-remount of safely removed or ejected USB-3 devices Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 22:40 +0100
[PATCH 4.4 35/60] ext4: fix in-superblock mount options processing Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 22:40 +0100
[PATCH 4.4 15/60] ALSA: hda/ca0132 - Add quirk for Alienware 15 R2 2016 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 22:50 +0100
[PATCH 4.4 13/60] ALSA: usb-audio: Add QuickCam Communicate Deluxe/S7500 to volume_control_quirks Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-04 22:50 +0100
Re: [PATCH 4.4 00/60] 4.4.40-stable review Shuah Khan <shuah.kh@samsung.com> - 2017-01-05 01:50 +0100
Re: [PATCH 4.4 00/60] 4.4.40-stable review Guenter Roeck <linux@roeck-us.net> - 2017-01-05 06:30 +0100
Re: [PATCH 4.4 00/60] 4.4.40-stable review Guillaume Nault <g.nault@alphalink.fr> - 2017-01-05 16:50 +0100
Re: [PATCH 4.4 00/60] 4.4.40-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-01-05 21:40 +0100
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