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  1. 15 8月, 2019 2 次提交
    • F
      x86/cpufeatures: Combine word 11 and 12 into a new scattered features word · 74f65670
      由 Fenghua Yu 提交于 
      commit acec0ce081de0c36459eea91647faf99296445a3 upstream.

It's a waste for the four X86_FEATURE_CQM_* feature bits to occupy two
whole feature bits words. To better utilize feature words, re-define
word 11 to host scattered features and move the four X86_FEATURE_CQM_*
features into Linux defined word 11. More scattered features can be
added in word 11 in the future.

Rename leaf 11 in cpuid_leafs to CPUID_LNX_4 to reflect it's a
Linux-defined leaf.

Rename leaf 12 as CPUID_DUMMY which will be replaced by a meaningful
name in the next patch when CPUID.7.1:EAX occupies world 12.

Maximum number of RMID and cache occupancy scale are retrieved from
CPUID.0xf.1 after scattered CQM features are enumerated. Carve out the
code into a separate function.

KVM doesn't support resctrl now. So it's safe to move the
X86_FEATURE_CQM_* features to scattered features word 11 for KVM.
Signed-off-by: NFenghua Yu <fenghua.yu@intel.com>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Aaron Lewis <aaronlewis@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Babu Moger <babu.moger@amd.com>
Cc: "Chang S. Bae" <chang.seok.bae@intel.com>
Cc: "Sean J Christopherson" <sean.j.christopherson@intel.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: kvm ML <kvm@vger.kernel.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Peter Feiner <pfeiner@google.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Ravi V Shankar <ravi.v.shankar@intel.com>
Cc: Sherry Hurwitz <sherry.hurwitz@amd.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thomas Lendacky <Thomas.Lendacky@amd.com>
Cc: x86 <x86@kernel.org>
Link: https://lkml.kernel.org/r/1560794416-217638-2-git-send-email-fenghua.yu@intel.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
      74f65670
    • B
      x86/cpufeatures: Carve out CQM features retrieval · deaf49f3
      由 Borislav Petkov 提交于 
      commit 45fc56e629caa451467e7664fbd4c797c434a6c4 upstream.

... into a separate function for better readability. Split out from a
patch from Fenghua Yu <fenghua.yu@intel.com> to keep the mechanical,
sole code movement separate for easy review.

No functional changes.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: x86@kernel.org
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
      deaf49f3
  3. 06 8月, 2019 13 次提交
    • E
      ext4: fix bigalloc cluster freeing when hole punching under load · 46de2e5e
      由 Eric Whitney 提交于 
      commit 7bd75230b43727b258a4f7a59d62114cffe1b6c8 upstream.

Ext4 may not free clusters correctly when punching holes in bigalloc
file systems under high load conditions.  If it's not possible to
extend and restart the journal in ext4_ext_rm_leaf() when preparing to
remove blocks from a punched region, a retry of the entire punch
operation is triggered in ext4_ext_remove_space().  This causes a
partial cluster to be set to the first cluster in the extent found to
the right of the punched region.  However, if the punch operation
prior to the retry had made enough progress to delete one or more
extents and a partial cluster candidate for freeing had already been
recorded, the retry would overwrite the partial cluster.  The loss of
this information makes it impossible to correctly free the original
partial cluster in all cases.

This bug can cause generic/476 to fail when run as part of
xfstests-bld's bigalloc and bigalloc_1k test cases.  The failure is
reported when e2fsck detects bad iblocks counts greater than expected
in units of whole clusters and also detects a number of negative block
bitmap differences equal to the iblocks discrepancy in cluster units.
Signed-off-by: NEric Whitney <enwlinux@gmail.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
      46de2e5e
    • G
      ext4: fix build error when DX_DEBUG is defined · f2d52aff
      由 Gabriel Krisman Bertazi 提交于 
      commit 799578ab16e86b074c184ec5abbda0bc698c7b0b upstream.

Enabling DX_DEBUG triggers the build error below.  info is an attribute
of  the dxroot structure.

linux/fs/ext4/namei.c:2264:12: error: ‘info’
undeclared (first use in this function); did you mean ‘insl’?
	   	  info->indirect_levels));

Fixes: e08ac99f ("ext4: add largedir feature")
Signed-off-by: NGabriel Krisman Bertazi <krisman@collabora.co.uk>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
Reviewed-by: NLukas Czerner <lczerner@redhat.com>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>
      f2d52aff
    • D
      mm/page-writeback.c: fix range_cyclic writeback vs writepages deadlock · b6962996
      由 Dave Chinner 提交于 
      commit 64081362e8ff4587b4554087f3cfc73d3e0a4cd7 upstream.

We've recently seen a workload on XFS filesystems with a repeatable
deadlock between background writeback and a multi-process application
doing concurrent writes and fsyncs to a small range of a file.

range_cyclic
writeback		Process 1		Process 2

xfs_vm_writepages
  write_cache_pages
    writeback_index = 2
    cycled = 0
    ....
    find page 2 dirty
    lock Page 2
    ->writepage
      page 2 writeback
      page 2 clean
      page 2 added to bio
    no more pages
			write()
			locks page 1
			dirties page 1
			locks page 2
			dirties page 1
			fsync()
			....
			xfs_vm_writepages
			write_cache_pages
			  start index 0
			  find page 1 towrite
			  lock Page 1
			  ->writepage
			    page 1 writeback
			    page 1 clean
			    page 1 added to bio
			  find page 2 towrite
			  lock Page 2
			  page 2 is writeback
			  <blocks>
						write()
						locks page 1
						dirties page 1
						fsync()
						....
						xfs_vm_writepages
						write_cache_pages
						  start index 0

    !done && !cycled
      sets index to 0, restarts lookup
    find page 1 dirty
						  find page 1 towrite
						  lock Page 1
						  page 1 is writeback
						  <blocks>

    lock Page 1
    <blocks>

DEADLOCK because:

	- process 1 needs page 2 writeback to complete to make
	  enough progress to issue IO pending for page 1
	- writeback needs page 1 writeback to complete so process 2
	  can progress and unlock the page it is blocked on, then it
	  can issue the IO pending for page 2
	- process 2 can't make progress until process 1 issues IO
	  for page 1

The underlying cause of the problem here is that range_cyclic writeback is
processing pages in descending index order as we hold higher index pages
in a structure controlled from above write_cache_pages().  The
write_cache_pages() caller needs to be able to submit these pages for IO
before write_cache_pages restarts writeback at mapping index 0 to avoid
wcp inverting the page lock/writeback wait order.

generic_writepages() is not susceptible to this bug as it has no private
context held across write_cache_pages() - filesystems using this
infrastructure always submit pages in ->writepage immediately and so there
is no problem with range_cyclic going back to mapping index 0.

However:
	mpage_writepages() has a private bio context,
	exofs_writepages() has page_collect
	fuse_writepages() has fuse_fill_wb_data
	nfs_writepages() has nfs_pageio_descriptor
	xfs_vm_writepages() has xfs_writepage_ctx

All of these ->writepages implementations can hold pages under writeback
in their private structures until write_cache_pages() returns, and hence
they are all susceptible to this deadlock.

Also worth noting is that ext4 has it's own bastardised version of
write_cache_pages() and so it /may/ have an equivalent deadlock.  I looked
at the code long enough to understand that it has a similar retry loop for
range_cyclic writeback reaching the end of the file and then promptly ran
away before my eyes bled too much.  I'll leave it for the ext4 developers
to determine if their code is actually has this deadlock and how to fix it
if it has.

There's a few ways I can see avoid this deadlock.  There's probably more,
but these are the first I've though of:

1. get rid of range_cyclic altogether

2. range_cyclic always stops at EOF, and we start again from
writeback index 0 on the next call into write_cache_pages()

2a. wcp also returns EAGAIN to ->writepages implementations to
indicate range cyclic has hit EOF. writepages implementations can
then flush the current context and call wpc again to continue. i.e.
lift the retry into the ->writepages implementation

3. range_cyclic uses trylock_page() rather than lock_page(), and it
skips pages it can't lock without blocking. It will already do this
for pages under writeback, so this seems like a no-brainer

3a. all non-WB_SYNC_ALL writeback uses trylock_page() to avoid
blocking as per pages under writeback.

I don't think #1 is an option - range_cyclic prevents frequently
dirtied lower file offset from starving background writeback of
rarely touched higher file offsets.

performance as going back to the start of the file implies an
immediate seek. We'll have exactly the same number of seeks if we
switch writeback to another inode, and then come back to this one
later and restart from index 0.

retry loop up into the wcp caller means we can issue IO on the
pending pages before calling wcp again, and so avoid locking or
waiting on pages in the wrong order. I'm not convinced we need to do
this given that we get the same thing from #2 on the next writeback
call from the writeback infrastructure.

inversion problem, just prevents it from becoming a deadlock
situation. I'd prefer we fix the inversion, not sweep it under the
carpet like this.

band-aid fix of #3.

So it seems that the simplest way to fix this issue is to implement
solution #2

Link: http://lkml.kernel.org/r/20181005054526.21507-1-david@fromorbit.comSigned-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NJan Kara <jack@suse.de>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>
      b6962996
    • M
      block: fix single range discard merge · 408d2591
      由 Ming Lei 提交于 
      commit 2a5cf35cd6c56b2924bce103413ad3381bdc31fa upstream.

There are actually two kinds of discard merge:

- one is the normal discard merge, just like normal read/write request,
and call it single-range discard

- another is the multi-range discard, queue_max_discard_segments(rq->q) > 1

For the former case, queue_max_discard_segments(rq->q) is 1, and we
should handle this kind of discard merge like the normal read/write
request.

This patch fixes the following kernel panic issue[1], which is caused by
not removing the single-range discard request from elevator queue.

Guangwu has one raid discard test case, in which this issue is a bit
easier to trigger, and I verified that this patch can fix the kernel
panic issue in Guangwu's test case.

[1] kernel panic log from Jens's report

 BUG: unable to handle kernel NULL pointer dereference at 0000000000000148
 PGD 0 P4D 0.
 Oops: 0000 [#1] SMP PTI
 CPU: 37 PID: 763 Comm: kworker/37:1H Not tainted \
4.20.0-rc3-00649-ge64d9a554a91-dirty #14  Hardware name: Wiwynn \
Leopard-Orv2/Leopard-DDR BW, BIOS LBM08   03/03/2017       Workqueue: kblockd \
blk_mq_run_work_fn                                            RIP: \
0010:blk_mq_get_driver_tag+0x81/0x120                                       Code: 24 \
10 48 89 7c 24 20 74 21 83 fa ff 0f 95 c0 48 8b 4c 24 28 65 48 33 0c 25 28 00 00 00 \
0f 85 96 00 00 00 48 83 c4 30 5b 5d c3 <48> 8b 87 48 01 00 00 8b 40 04 39 43 20 72 37 \
f6 87 b0 00 00 00 02  RSP: 0018:ffffc90004aabd30 EFLAGS: 00010246                     \
  RAX: 0000000000000003 RBX: ffff888465ea1300 RCX: ffffc90004aabde8
 RDX: 00000000ffffffff RSI: ffffc90004aabde8 RDI: 0000000000000000
 RBP: 0000000000000000 R08: ffff888465ea1348 R09: 0000000000000000
 R10: 0000000000001000 R11: 00000000ffffffff R12: ffff888465ea1300
 R13: 0000000000000000 R14: ffff888465ea1348 R15: ffff888465d10000
 FS:  0000000000000000(0000) GS:ffff88846f9c0000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 0000000000000148 CR3: 000000000220a003 CR4: 00000000003606e0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 Call Trace:
  blk_mq_dispatch_rq_list+0xec/0x480
  ? elv_rb_del+0x11/0x30
  blk_mq_do_dispatch_sched+0x6e/0xf0
  blk_mq_sched_dispatch_requests+0xfa/0x170
  __blk_mq_run_hw_queue+0x5f/0xe0
  process_one_work+0x154/0x350
  worker_thread+0x46/0x3c0
  kthread+0xf5/0x130
  ? process_one_work+0x350/0x350
  ? kthread_destroy_worker+0x50/0x50
  ret_from_fork+0x1f/0x30
 Modules linked in: sb_edac x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel \
kvm switchtec irqbypass iTCO_wdt iTCO_vendor_support efivars cdc_ether usbnet mii \
cdc_acm i2c_i801 lpc_ich mfd_core ipmi_si ipmi_devintf ipmi_msghandler acpi_cpufreq \
button sch_fq_codel nfsd nfs_acl lockd grace auth_rpcgss oid_registry sunrpc nvme \
nvme_core fuse sg loop efivarfs autofs4  CR2: 0000000000000148                        \

 ---[ end trace 340a1fb996df1b9b ]---
 RIP: 0010:blk_mq_get_driver_tag+0x81/0x120
 Code: 24 10 48 89 7c 24 20 74 21 83 fa ff 0f 95 c0 48 8b 4c 24 28 65 48 33 0c 25 28 \
00 00 00 0f 85 96 00 00 00 48 83 c4 30 5b 5d c3 <48> 8b 87 48 01 00 00 8b 40 04 39 43 \
20 72 37 f6 87 b0 00 00 00 02

Fixes: 445251d0 ("blk-mq: fix discard merge with scheduler attached")
Reported-by: NJens Axboe <axboe@kernel.dk>
Cc: Guangwu Zhang <guazhang@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>
      408d2591
    • O
      NFSv4.x: fix lock recovery during delegation recall · d50ef120
      由 Olga Kornievskaia 提交于 
      commit 44f411c353bf6d98d5a34f8f1b8605d43b2e50b8 upstream.

Running "./nfstest_delegation --runtest recall26" uncovers that
client doesn't recover the lock when we have an appending open,
where the initial open got a write delegation.

Instead of checking for the passed in open context against
the file lock's open context. Check that the state is the same.
Signed-off-by: NOlga Kornievskaia <kolga@netapp.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>
      d50ef120
    • J
      block: fix the DISCARD request merge · e5151915
      由 Jianchao Wang 提交于 
      commit 69840466086d2248898020a08dda52732686c4e6 upstream.

There are two cases when handle DISCARD merge.
If max_discard_segments == 1, the bios/requests need to be contiguous
to merge. If max_discard_segments > 1, it takes every bio as a range
and different range needn't to be contiguous.

But now, attempt_merge screws this up. It always consider contiguity
for DISCARD for the case max_discard_segments > 1 and cannot merge
contiguous DISCARD for the case max_discard_segments == 1, because
rq_attempt_discard_merge always returns false in this case.
This patch fixes both of the two cases above.
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NMing Lei <ming.lei@redhat.com>
Signed-off-by: NJianchao Wang <jianchao.w.wang@oracle.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>
      e5151915
    • H
      dm raid: fix false -EBUSY when handling check/repair message · 71e612b3
      由 Heinz Mauelshagen 提交于 
      commit 74694bcbdf7e28a5ad548cdda9ac56d30be00d13 upstream.

Sending a check/repair message infrequently leads to -EBUSY instead of
properly identifying an active resync.  This occurs because
raid_message() is testing recovery bits in a racy way.

Fix by calling decipher_sync_action() from raid_message() to properly
identify the idle state of the RAID device.
Signed-off-by: NHeinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>
      71e612b3
    • D
      xfs: fix use-after-free race in xfs_buf_rele · ac911480
      由 Dave Chinner 提交于 
      commit 37fd1678245f7a5898c1b05128bc481fb403c290 upstream.

When looking at a 4.18 based KASAN use after free report, I noticed
that racing xfs_buf_rele() may race on dropping the last reference
to the buffer and taking the buffer lock. This was the symptom
displayed by the KASAN report, but the actual issue that was
reported had already been fixed in 4.19-rc1 by commit e339dd8d
("xfs: use sync buffer I/O for sync delwri queue submission").

Despite this, I think there is still an issue with xfs_buf_rele()
in this code:

        release = atomic_dec_and_lock(&bp->b_hold, &pag->pag_buf_lock);
        spin_lock(&bp->b_lock);
        if (!release) {
.....

If two threads race on the b_lock after both dropping a reference
and one getting dropping the last reference so release = true, we
end up with:

CPU 0				CPU 1
atomic_dec_and_lock()
				atomic_dec_and_lock()
				spin_lock(&bp->b_lock)
spin_lock(&bp->b_lock)
<spins>
				<release = true bp->b_lru_ref = 0>
				<remove from lists>
				freebuf = true
				spin_unlock(&bp->b_lock)
				xfs_buf_free(bp)
<gets lock, reading and writing freed memory>
<accesses freed memory>
spin_unlock(&bp->b_lock) <reads/writes freed memory>

IOWs, we can't safely take bp->b_lock after dropping the hold
reference because the buffer may go away at any time after we
drop that reference. However, this can be fixed simply by taking the
bp->b_lock before we drop the reference.

It is safe to nest the pag_buf_lock inside bp->b_lock as the
pag_buf_lock is only used to serialise against lookup in
xfs_buf_find() and no other locks are held over or under the
pag_buf_lock there. Make this clear by documenting the buffer lock
orders at the top of the file.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com
Signed-off-by: NDave Chinner <david@fromorbit.com>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>
      ac911480
    • W
      x86: uaccess: Inhibit speculation past access_ok() in user_access_begin() · e28b4155
      由 Will Deacon 提交于 
      commit 6e693b3ffecb0b478c7050b44a4842854154f715 upstream.

Commit 594cc251fdd0 ("make 'user_access_begin()' do 'access_ok()'")
makes the access_ok() check part of the user_access_begin() preceding a
series of 'unsafe' accesses.  This has the desirable effect of ensuring
that all 'unsafe' accesses have been range-checked, without having to
pick through all of the callsites to verify whether the appropriate
checking has been made.

However, the consolidated range check does not inhibit speculation, so
it is still up to the caller to ensure that they are not susceptible to
any speculative side-channel attacks for user addresses that ultimately
fail the access_ok() check.

This is an oversight, so use __uaccess_begin_nospec() to ensure that
speculation is inhibited until the access_ok() check has passed.
Reported-by: NJulien Thierry <julien.thierry@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
      e28b4155
    • L
      make 'user_access_begin()' do 'access_ok()' · aba1b548
      由 Linus Torvalds 提交于 
      commit 594cc251fdd0d231d342d88b2fdff4bc42fb0690 upstream.

Originally, the rule used to be that you'd have to do access_ok()
separately, and then user_access_begin() before actually doing the
direct (optimized) user access.

But experience has shown that people then decide not to do access_ok()
at all, and instead rely on it being implied by other operations or
similar.  Which makes it very hard to verify that the access has
actually been range-checked.

If you use the unsafe direct user accesses, hardware features (either
SMAP - Supervisor Mode Access Protection - on x86, or PAN - Privileged
Access Never - on ARM) do force you to use user_access_begin().  But
nothing really forces the range check.

By putting the range check into user_access_begin(), we actually force
people to do the right thing (tm), and the range check vill be visible
near the actual accesses.  We have way too long a history of people
trying to avoid them.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

[ Shile: fix following conflicts by adding a dummy arguments ]
Conflicts:
	kernel/compat.c
	kernel/exit.c
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>
      aba1b548
    • L
      i915: fix missing user_access_end() in page fault exception case · 22698330
      由 Linus Torvalds 提交于 
      commit 0b2c8f8b6b0c7530e2866c95862546d0da2057b0 upstream.

When commit fddcd00a49e9 ("drm/i915: Force the slow path after a
user-write error") unified the error handling for various user access
problems, it didn't do the user_access_end() that is needed for the
unsafe_put_user() case.

It's not a huge deal: a missed user_access_end() will only mean that
SMAP protection isn't active afterwards, and for the error case we'll be
returning to user mode soon enough anyway.  But it's wrong, and adding
the proper user_access_end() is trivial enough (and doing it for the
other error cases where it isn't needed doesn't hurt).

I noticed it while doing the same prep-work for changing
user_access_begin() that precipitated the access_ok() changes in commit
96d4f267e40f ("Remove 'type' argument from access_ok() function").

Fixes: fddcd00a49e9 ("drm/i915: Force the slow path after a user-write error")
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: stable@kernel.org # v4.20
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
      22698330
    • C
      drm/i915: Force the slow path after a user-write error · 5cbce514
      由 Chris Wilson 提交于 
      commit fddcd00a49e9122a3579247151e9cb3ce5a1a36e upstream.

If we fail to write the user relocation back when it is changed, force
ourselves to take the slow relocation path where we can handle faults in
the write path. There is still an element of dubiousness as having
patched up the batch to use the correct offset, it no longer matches the
presumed_offset in the relocation, so a second pass may miss any changes
in layout.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180903083337.13134-3-chris@chris-wilson.co.ukSigned-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
      5cbce514
    • A
      userfaultfd: allow get_mempolicy(MPOL_F_NODE|MPOL_F_ADDR) to trigger userfaults · c15f4d67
      由 Andrea Arcangeli 提交于 
      commit 3b9aadf7278d16d7bed4d5d808501065f70898d8 upstream.

get_mempolicy(MPOL_F_NODE|MPOL_F_ADDR) called a get_user_pages that would
not be waiting for userfaults before failing and it would hit on a SIGBUS
instead.  Using get_user_pages_locked/unlocked instead will allow
get_mempolicy to allow userfaults to resolve the fault and fill the hole,
before grabbing the node id of the page.

If the user calls get_mempolicy() with MPOL_F_ADDR | MPOL_F_NODE for an
address inside an area managed by uffd and there is no page at that
address, the page allocation from within get_mempolicy() will fail
because get_user_pages() does not allow for page fault retry required
for uffd; the user will get SIGBUS.

With this patch, the page fault will be resolved by the uffd and the
get_mempolicy() will continue normally.

Background:

Via code review, previously the syscall would have returned -EFAULT
(vm_fault_to_errno), now it will block and wait for an userfault (if
it's waken before the fault is resolved it'll still -EFAULT).

This way get_mempolicy will give a chance to an "unaware" app to be
compliant with userfaults.

The reason this visible change is that becoming "userfault compliant"
cannot regress anything: all other syscalls including read(2)/write(2)
had to become "userfault compliant" long time ago (that's one of the
things userfaultfd can do that PROT_NONE and trapping segfaults can't).

So this is just one more syscall that become "userfault compliant" like
all other major ones already were.

This has been happening on virtio-bridge dpdk process which just called
get_mempolicy on the guest space post live migration, but before the
memory had a chance to be migrated to destination.

I didn't run an strace to be able to show the -EFAULT going away, but
I've the confirmation of the below debug aid information (only visible
with CONFIG_DEBUG_VM=y) going away with the patch:

    [20116.371461] FAULT_FLAG_ALLOW_RETRY missing 0
    [20116.371464] CPU: 1 PID: 13381 Comm: vhost-events Not tainted 4.17.12-200.fc28.x86_64 #1
    [20116.371465] Hardware name: LENOVO 20FAS2BN0A/20FAS2BN0A, BIOS N1CET54W (1.22 ) 02/10/2017
    [20116.371466] Call Trace:
    [20116.371473]  dump_stack+0x5c/0x80
    [20116.371476]  handle_userfault.cold.37+0x1b/0x22
    [20116.371479]  ? remove_wait_queue+0x20/0x60
    [20116.371481]  ? poll_freewait+0x45/0xa0
    [20116.371483]  ? do_sys_poll+0x31c/0x520
    [20116.371485]  ? radix_tree_lookup_slot+0x1e/0x50
    [20116.371488]  shmem_getpage_gfp+0xce7/0xe50
    [20116.371491]  ? page_add_file_rmap+0x1a/0x2c0
    [20116.371493]  shmem_fault+0x78/0x1e0
    [20116.371495]  ? filemap_map_pages+0x3a1/0x450
    [20116.371498]  __do_fault+0x1f/0xc0
    [20116.371500]  __handle_mm_fault+0xe2e/0x12f0
    [20116.371502]  handle_mm_fault+0xda/0x200
    [20116.371504]  __get_user_pages+0x238/0x790
    [20116.371506]  get_user_pages+0x3e/0x50
    [20116.371510]  kernel_get_mempolicy+0x40b/0x700
    [20116.371512]  ? vfs_write+0x170/0x1a0
    [20116.371515]  __x64_sys_get_mempolicy+0x21/0x30
    [20116.371517]  do_syscall_64+0x5b/0x160
    [20116.371520]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

The above harmless debug message (not a kernel crash, just a
dump_stack()) is shown with CONFIG_DEBUG_VM=y to more quickly identify
and improve kernel spots that may have to become "userfaultfd
compliant" like this one (without having to run an strace and search
for syscall misbehavior).  Spots like the above are more closer to a
kernel bug for the non-cooperative usages that Mike focuses on, than
for for dpdk qemu-cooperative usages that reproduced it, but it's still
nicer to get this fixed for dpdk too.

The part of the patch that caused me to think is only the
implementation issue of mpol_get, but it looks like it should work safe
no matter the kind of mempolicy structure that is (the default static
policy also starts at 1 so it'll go to 2 and back to 1 without crashing
everything at 0).

[rppt@linux.vnet.ibm.com: changelog addition]
  http://lkml.kernel.org/r/20180904073718.GA26916@rapoport-lnx
Link: http://lkml.kernel.org/r/20180831214848.23676-1-aarcange@redhat.comSigned-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Reported-by: NMaxime Coquelin <maxime.coquelin@redhat.com>
Tested-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: NMike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
      c15f4d67
  5. 01 8月, 2019 2 次提交
  7. 29 7月, 2019 3 次提交
  9. 25 7月, 2019 1 次提交
    • J
      ptrace: Fix ->ptracer_cred handling for PTRACE_TRACEME · 4cf85eef
      由 Jann Horn 提交于 
      commit 6994eefb0053799d2e07cd140df6c2ea106c41ee upstream.

This fixes CVE-2019-13272.

Fix two issues:

When called for PTRACE_TRACEME, ptrace_link() would obtain an RCU
reference to the parent's objective credentials, then give that pointer
to get_cred().  However, the object lifetime rules for things like
struct cred do not permit unconditionally turning an RCU reference into
a stable reference.

PTRACE_TRACEME records the parent's credentials as if the parent was
acting as the subject, but that's not the case.  If a malicious
unprivileged child uses PTRACE_TRACEME and the parent is privileged, and
at a later point, the parent process becomes attacker-controlled
(because it drops privileges and calls execve()), the attacker ends up
with control over two processes with a privileged ptrace relationship,
which can be abused to ptrace a suid binary and obtain root privileges.

Fix both of these by always recording the credentials of the process
that is requesting the creation of the ptrace relationship:
current_cred() can't change under us, and current is the proper subject
for access control.

This change is theoretically userspace-visible, but I am not aware of
any code that it will actually break.

Fixes: 64b875f7 ("ptrace: Capture the ptracer's creds not PT_PTRACE_CAP")
Signed-off-by: NJann Horn <jannh@google.com>
Acked-by: NOleg Nesterov <oleg@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NShile Zhang <shile.zhang@linux.alibaba.com>
Acked-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
      4cf85eef
  11. 24 7月, 2019 5 次提交
  13. 20 7月, 2019 1 次提交
  15. 18 7月, 2019 1 次提交
    • X
      ext4: unlock unused_pages timely when doing writeback · 404ed43a
      由 Xiaoguang Wang 提交于 
      commit a297b2fcee461e40df763e179cbbfba5a9e572d2 upstream.

In mpage_add_bh_to_extent(), when accumulated extents length is greater
than MAX_WRITEPAGES_EXTENT_LEN or buffer head's b_stat is not equal, we
will not continue to search unmapped area for this page, but note this
page is locked, and will only be unlocked in mpage_release_unused_pages()
after ext4_io_submit, if io also is throttled by blk-throttle or similar
io qos, we will hold this page locked for a while, it's unnecessary.

I think the best fix is to refactor mpage_add_bh_to_extent() to let it
return some hints whether to unlock this page, but given that we will
improve dioread_nolock later, we can let it done later, so currently
the simple fix would just call mpage_release_unused_pages() before
ext4_io_submit().
Signed-off-by: NXiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: NLiu Bo <bo.liu@linux.alibaba.com>
      404ed43a
  17. 10 7月, 2019 1 次提交
  19. 05 7月, 2019 11 次提交