linux.git/fs/proc/vmcore.c, branch v6.3

mm: replace vma->vm_flags direct modifications with modifier calls

2023-02-10T00:51:39+00:00

Replace direct modifications to vma->vm_flags with calls to modifier
functions to be able to track flag changes and to keep vma locking
correctness.

[akpm@linux-foundation.org: fix drivers/misc/open-dice.c, per Hyeonggon Yoo]
Link: https://lkml.kernel.org/r/20230126193752.297968-5-surenb@google.com
Signed-off-by: Suren Baghdasaryan 
Acked-by: Michal Hocko 
Acked-by: Mel Gorman 
Acked-by: Mike Rapoport (IBM) 
Acked-by: Sebastian Reichel 
Reviewed-by: Liam R. Howlett 
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Andy Lutomirski 
Cc: Arjun Roy 
Cc: Axel Rasmussen 
Cc: David Hildenbrand 
Cc: David Howells 
Cc: Davidlohr Bueso 
Cc: David Rientjes 
Cc: Eric Dumazet 
Cc: Greg Thelen 
Cc: Hugh Dickins 
Cc: Ingo Molnar 
Cc: Jann Horn 
Cc: Joel Fernandes 
Cc: Johannes Weiner 
Cc: Kent Overstreet 
Cc: Laurent Dufour 
Cc: Lorenzo Stoakes 
Cc: Matthew Wilcox 
Cc: Minchan Kim 
Cc: Paul E. McKenney 
Cc: Peter Oskolkov 
Cc: Peter Xu 
Cc: Peter Zijlstra 
Cc: Punit Agrawal 
Cc: Sebastian Andrzej Siewior 
Cc: Shakeel Butt 
Cc: Soheil Hassas Yeganeh 
Cc: Song Liu 
Cc: Vlastimil Babka 
Cc: Will Deacon 
Signed-off-by: Andrew Morton

Merge tag 'pull-iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2022-12-13T02:29:54+00:00

Pull iov_iter updates from Al Viro:
 "iov_iter work; most of that is about getting rid of direction
  misannotations and (hopefully) preventing more of the same for the
  future"

* tag 'pull-iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  use less confusing names for iov_iter direction initializers
  iov_iter: saner checks for attempt to copy to/from iterator
  [xen] fix "direction" argument of iov_iter_kvec()
  [vhost] fix 'direction' argument of iov_iter_{init,bvec}()
  [target] fix iov_iter_bvec() "direction" argument
  [s390] memcpy_real(): WRITE is "data source", not destination...
  [s390] zcore: WRITE is "data source", not destination...
  [infiniband] READ is "data destination", not source...
  [fsi] WRITE is "data source", not destination...
  [s390] copy_oldmem_kernel() - WRITE is "data source", not destination
  csum_and_copy_to_iter(): handle ITER_DISCARD
  get rid of unlikely() on page_copy_sane() calls

use less confusing names for iov_iter direction initializers

2022-11-25T18:01:55+00:00

READ/WRITE proved to be actively confusing - the meanings are
"data destination, as used with read(2)" and "data source, as
used with write(2)", but people keep interpreting those as
"we read data from it" and "we write data to it", i.e. exactly
the wrong way.

Call them ITER_DEST and ITER_SOURCE - at least that is harder
to misinterpret...

Signed-off-by: Al Viro

proc/vmcore: fix potential memory leak in vmcore_init()

2022-11-18T21:55:06+00:00

Patch series "Some minor cleanup patches resent".

The first three patches trivial clean up patches.

And for the patch "kexec: replace crash_mem_range with range", I got a
ibm-p9wr ppc64le system to test, it works well.


This patch (of 4):

elfcorehdr_alloc() allocates a memory chunk for elfcorehdr_addr with
kzalloc().  If is_vmcore_usable() returns false, elfcorehdr_addr is a
predefined value.  If parse_crash_elf_headers() gets some error and
returns a negetive value, the elfcorehdr_addr should be released with
elfcorehdr_free().

Fix it by calling elfcorehdr_free() when parse_crash_elf_headers() fails.

Link: https://lkml.kernel.org/r/20220929042936.22012-1-bhe@redhat.com
Link: https://lkml.kernel.org/r/20220929042936.22012-2-bhe@redhat.com
Signed-off-by: Jianglei Nie 
Signed-off-by: Baoquan He 
Acked-by: Baoquan He 
Cc: Benjamin Herrenschmidt 
Cc: Chen Lifu 
Cc: "Eric W . Biederman" 
Cc: Li Chen 
Cc: Michael Ellerman 
Cc: Paul Mackerras 
Cc: Petr Mladek 
Cc: Russell King 
Cc: ye xingchen 
Cc: Zeal Robot 
Signed-off-by: Andrew Morton

proc: delete unused includes

2022-07-18T00:31:39+00:00

Those aren't necessary after seq files won.

Link: https://lkml.kernel.org/r/YqnA3mS7KBt8Z4If@localhost.localdomain
Signed-off-by: Alexey Dobriyan 
Signed-off-by: Andrew Morton

vmcore: convert read_from_oldmem() to take an iov_iter

2022-04-29T21:37:59+00:00

Remove the read_from_oldmem() wrapper introduced earlier and convert all
the remaining callers to pass an iov_iter.

Link: https://lkml.kernel.org/r/20220408090636.560886-4-bhe@redhat.com
Signed-off-by: Matthew Wilcox (Oracle) 
Signed-off-by: Baoquan He 
Reviewed-by: Christoph Hellwig 
Cc: Tiezhu Yang 
Cc: Amit Daniel Kachhap 
Cc: Al Viro 
Cc: Matthew Wilcox 
Signed-off-by: Andrew Morton

vmcore: convert __read_vmcore to use an iov_iter

2022-04-29T21:37:59+00:00

This gets rid of copy_to() and let us use proc_read_iter() instead of
proc_read().

Link: https://lkml.kernel.org/r/20220408090636.560886-3-bhe@redhat.com
Signed-off-by: Matthew Wilcox (Oracle) 
Signed-off-by: Baoquan He 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Andrew Morton

vmcore: convert copy_oldmem_page() to take an iov_iter

2022-04-29T21:37:59+00:00

Patch series "Convert vmcore to use an iov_iter", v5.

For some reason several people have been sending bad patches to fix
compiler warnings in vmcore recently.  Here's how it should be done. 
Compile-tested only on x86.  As noted in the first patch, s390 should take
this conversion a bit further, but I'm not inclined to do that work
myself.


This patch (of 3):

Instead of passing in a 'buf' and 'userbuf' argument, pass in an iov_iter.
s390 needs more work to pass the iov_iter down further, or refactor, but
I'd be more comfortable if someone who can test on s390 did that work.

It's more convenient to convert the whole of read_from_oldmem() to take an
iov_iter at the same time, so rename it to read_from_oldmem_iter() and add
a temporary read_from_oldmem() wrapper that creates an iov_iter.

Link: https://lkml.kernel.org/r/20220408090636.560886-1-bhe@redhat.com
Link: https://lkml.kernel.org/r/20220408090636.560886-2-bhe@redhat.com
Signed-off-by: Matthew Wilcox (Oracle) 
Signed-off-by: Baoquan He 
Reviewed-by: Christoph Hellwig 
Cc: Heiko Carstens 
Signed-off-by: Andrew Morton

proc/vmcore: fix vmcore_alloc_buf() kernel-doc comment

2022-03-24T02:00:33+00:00

Fix a spelling problem to remove warnings found by running
scripts/kernel-doc, which is caused by using 'make W=1'.

  fs/proc/vmcore.c:492: warning: Function parameter or member 'size' not described in 'vmcore_alloc_buf'
  fs/proc/vmcore.c:492: warning: Excess function parameter 'sizez' description in 'vmcore_alloc_buf'

Link: https://lkml.kernel.org/r/20220129011449.105278-1-yang.lee@linux.alibaba.com
Signed-off-by: Yang Li 
Reported-by: Abaci Robot 
Acked-by: Baoquan He 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc/vmcore: fix possible deadlock on concurrent mmap and read

2022-03-24T02:00:33+00:00

Lockdep noticed that there is chance for a deadlock if we have concurrent
mmap, concurrent read, and the addition/removal of a callback.

As nicely explained by Boqun:
 "Lockdep warned about the above sequences because rw_semaphore is a
  fair read-write lock, and the following can cause a deadlock:

	TASK 1			TASK 2		TASK 3
	======			======		======
	down_write(mmap_lock);
				down_read(vmcore_cb_rwsem)
						down_write(vmcore_cb_rwsem); // blocked
	down_read(vmcore_cb_rwsem); // cannot get the lock because of the fairness
				down_read(mmap_lock); // blocked

  IOW, a reader can block another read if there is a writer queued by
  the second reader and the lock is fair"

To fix this, convert to srcu to make this deadlock impossible.  We need
srcu as our callbacks can sleep.  With this change, I cannot trigger any
lockdep warnings.

    ======================================================
    WARNING: possible circular locking dependency detected
    5.17.0-0.rc0.20220117git0c947b893d69.68.test.fc36.x86_64 #1 Not tainted
    ------------------------------------------------------
    makedumpfile/542 is trying to acquire lock:
    ffffffff832d2eb8 (vmcore_cb_rwsem){.+.+}-{3:3}, at: mmap_vmcore+0x340/0x580

    but task is already holding lock:
    ffff8880af226438 (&mm->mmap_lock#2){++++}-{3:3}, at: vm_mmap_pgoff+0x84/0x150

    which lock already depends on the new lock.

    the existing dependency chain (in reverse order) is:

    -> #1 (&mm->mmap_lock#2){++++}-{3:3}:
           lock_acquire+0xc3/0x1a0
           __might_fault+0x4e/0x70
           _copy_to_user+0x1f/0x90
           __copy_oldmem_page+0x72/0xc0
           read_from_oldmem+0x77/0x1e0
           read_vmcore+0x2c2/0x310
           proc_reg_read+0x47/0xa0
           vfs_read+0x101/0x340
           __x64_sys_pread64+0x5d/0xa0
           do_syscall_64+0x43/0x90
           entry_SYSCALL_64_after_hwframe+0x44/0xae

    -> #0 (vmcore_cb_rwsem){.+.+}-{3:3}:
           validate_chain+0x9f4/0x2670
           __lock_acquire+0x8f7/0xbc0
           lock_acquire+0xc3/0x1a0
           down_read+0x4a/0x140
           mmap_vmcore+0x340/0x580
           proc_reg_mmap+0x3e/0x90
           mmap_region+0x504/0x880
           do_mmap+0x38a/0x520
           vm_mmap_pgoff+0xc1/0x150
           ksys_mmap_pgoff+0x178/0x200
           do_syscall_64+0x43/0x90
           entry_SYSCALL_64_after_hwframe+0x44/0xae

    other info that might help us debug this:

     Possible unsafe locking scenario:

           CPU0                    CPU1
           ----                    ----
      lock(&mm->mmap_lock#2);
                                   lock(vmcore_cb_rwsem);
                                   lock(&mm->mmap_lock#2);
      lock(vmcore_cb_rwsem);

     *** DEADLOCK ***

    1 lock held by makedumpfile/542:
     #0: ffff8880af226438 (&mm->mmap_lock#2){++++}-{3:3}, at: vm_mmap_pgoff+0x84/0x150

    stack backtrace:
    CPU: 0 PID: 542 Comm: makedumpfile Not tainted 5.17.0-0.rc0.20220117git0c947b893d69.68.test.fc36.x86_64 #1
    Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
    Call Trace:
     __lock_acquire+0x8f7/0xbc0
     lock_acquire+0xc3/0x1a0
     down_read+0x4a/0x140
     mmap_vmcore+0x340/0x580
     proc_reg_mmap+0x3e/0x90
     mmap_region+0x504/0x880
     do_mmap+0x38a/0x520
     vm_mmap_pgoff+0xc1/0x150
     ksys_mmap_pgoff+0x178/0x200
     do_syscall_64+0x43/0x90

Link: https://lkml.kernel.org/r/20220119193417.100385-1-david@redhat.com
Fixes: cc5f2704c934 ("proc/vmcore: convert oldmem_pfn_is_ram callback to more generic vmcore callbacks")
Signed-off-by: David Hildenbrand 
Reported-by: Baoquan He 
Acked-by: Baoquan He 
Cc: Vivek Goyal 
Cc: Dave Young 
Cc: "Paul E. McKenney" 
Cc: Josh Triplett 
Cc: Peter Zijlstra 
Cc: Boqun Feng 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds