Revision 6f6acb00514c10be35529402f36ad7a288f08c2e authored by Michal Hocko on 22 May 2014, 18:54:19 UTC, committed by Linus Torvalds on 23 May 2014, 16:37:29 UTC
Commit 284f39afeaa4 ("mm: memcg: push !mm handling out to page cache charge function") explicitly checks for page cache charges without any mm context (from kernel thread context[1]). This seemed to be the only possible case where memory could be charged without mm context so commit 03583f1a631c ("memcg: remove unnecessary !mm check from try_get_mem_cgroup_from_mm()") removed the mm check from get_mem_cgroup_from_mm(). This however caused another NULL ptr dereference during early boot when loopback kernel thread splices to tmpfs as reported by Stephan Kulow: BUG: unable to handle kernel NULL pointer dereference at 0000000000000360 IP: get_mem_cgroup_from_mm.isra.42+0x2b/0x60 Oops: 0000 [#1] SMP Modules linked in: btrfs dm_multipath dm_mod scsi_dh multipath raid10 raid456 async_raid6_recov async_memcpy async_pq raid6_pq async_xor xor async_tx raid1 raid0 md_mod parport_pc parport nls_utf8 isofs usb_storage iscsi_ibft iscsi_boot_sysfs arc4 ecb fan thermal nfs lockd fscache nls_iso8859_1 nls_cp437 sg st hid_generic usbhid af_packet sunrpc sr_mod cdrom ata_generic uhci_hcd virtio_net virtio_blk ehci_hcd usbcore ata_piix floppy processor button usb_common virtio_pci virtio_ring virtio edd squashfs loop ppa] CPU: 0 PID: 97 Comm: loop1 Not tainted 3.15.0-rc5-5-default #1 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 Call Trace: __mem_cgroup_try_charge_swapin+0x40/0xe0 mem_cgroup_charge_file+0x8b/0xd0 shmem_getpage_gfp+0x66b/0x7b0 shmem_file_splice_read+0x18f/0x430 splice_direct_to_actor+0xa2/0x1c0 do_lo_receive+0x5a/0x60 [loop] loop_thread+0x298/0x720 [loop] kthread+0xc6/0xe0 ret_from_fork+0x7c/0xb0 Also Branimir Maksimovic reported the following oops which is tiggered for the swapcache charge path from the accounting code for kernel threads: CPU: 1 PID: 160 Comm: kworker/u8:5 Tainted: P OE 3.15.0-rc5-core2-custom #159 Hardware name: System manufacturer System Product Name/MAXIMUSV GENE, BIOS 1903 08/19/2013 task: ffff880404e349b0 ti: ffff88040486a000 task.ti: ffff88040486a000 RIP: get_mem_cgroup_from_mm.isra.42+0x2b/0x60 Call Trace: __mem_cgroup_try_charge_swapin+0x45/0xf0 mem_cgroup_charge_file+0x9c/0xe0 shmem_getpage_gfp+0x62c/0x770 shmem_write_begin+0x38/0x40 generic_perform_write+0xc5/0x1c0 __generic_file_aio_write+0x1d1/0x3f0 generic_file_aio_write+0x4f/0xc0 do_sync_write+0x5a/0x90 do_acct_process+0x4b1/0x550 acct_process+0x6d/0xa0 do_exit+0x827/0xa70 kthread+0xc3/0xf0 This patch fixes the issue by reintroducing mm check into get_mem_cgroup_from_mm. We could do the same trick in __mem_cgroup_try_charge_swapin as we do for the regular page cache path but it is not worth troubles. The check is not that expensive and it is better to have get_mem_cgroup_from_mm more robust. [1] - http://marc.info/?l=linux-mm&m=139463617808941&w=2 Fixes: 03583f1a631c ("memcg: remove unnecessary !mm check from try_get_mem_cgroup_from_mm()") Reported-and-tested-by: Stephan Kulow <coolo@suse.com> Reported-by: Branimir Maksimovic <branimir.maksimovic@gmail.com> Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Kconfig.locks
#
# The ARCH_INLINE foo is necessary because select ignores "depends on"
#
config ARCH_INLINE_SPIN_TRYLOCK
bool
config ARCH_INLINE_SPIN_TRYLOCK_BH
bool
config ARCH_INLINE_SPIN_LOCK
bool
config ARCH_INLINE_SPIN_LOCK_BH
bool
config ARCH_INLINE_SPIN_LOCK_IRQ
bool
config ARCH_INLINE_SPIN_LOCK_IRQSAVE
bool
config ARCH_INLINE_SPIN_UNLOCK
bool
config ARCH_INLINE_SPIN_UNLOCK_BH
bool
config ARCH_INLINE_SPIN_UNLOCK_IRQ
bool
config ARCH_INLINE_SPIN_UNLOCK_IRQRESTORE
bool
config ARCH_INLINE_READ_TRYLOCK
bool
config ARCH_INLINE_READ_LOCK
bool
config ARCH_INLINE_READ_LOCK_BH
bool
config ARCH_INLINE_READ_LOCK_IRQ
bool
config ARCH_INLINE_READ_LOCK_IRQSAVE
bool
config ARCH_INLINE_READ_UNLOCK
bool
config ARCH_INLINE_READ_UNLOCK_BH
bool
config ARCH_INLINE_READ_UNLOCK_IRQ
bool
config ARCH_INLINE_READ_UNLOCK_IRQRESTORE
bool
config ARCH_INLINE_WRITE_TRYLOCK
bool
config ARCH_INLINE_WRITE_LOCK
bool
config ARCH_INLINE_WRITE_LOCK_BH
bool
config ARCH_INLINE_WRITE_LOCK_IRQ
bool
config ARCH_INLINE_WRITE_LOCK_IRQSAVE
bool
config ARCH_INLINE_WRITE_UNLOCK
bool
config ARCH_INLINE_WRITE_UNLOCK_BH
bool
config ARCH_INLINE_WRITE_UNLOCK_IRQ
bool
config ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE
bool
config UNINLINE_SPIN_UNLOCK
bool
#
# lock_* functions are inlined when:
# - DEBUG_SPINLOCK=n and GENERIC_LOCKBREAK=n and ARCH_INLINE_*LOCK=y
#
# trylock_* functions are inlined when:
# - DEBUG_SPINLOCK=n and ARCH_INLINE_*LOCK=y
#
# unlock and unlock_irq functions are inlined when:
# - DEBUG_SPINLOCK=n and ARCH_INLINE_*LOCK=y
# or
# - DEBUG_SPINLOCK=n and PREEMPT=n
#
# unlock_bh and unlock_irqrestore functions are inlined when:
# - DEBUG_SPINLOCK=n and ARCH_INLINE_*LOCK=y
#
if !DEBUG_SPINLOCK
config INLINE_SPIN_TRYLOCK
def_bool y
depends on ARCH_INLINE_SPIN_TRYLOCK
config INLINE_SPIN_TRYLOCK_BH
def_bool y
depends on ARCH_INLINE_SPIN_TRYLOCK_BH
config INLINE_SPIN_LOCK
def_bool y
depends on !GENERIC_LOCKBREAK && ARCH_INLINE_SPIN_LOCK
config INLINE_SPIN_LOCK_BH
def_bool y
depends on !GENERIC_LOCKBREAK && ARCH_INLINE_SPIN_LOCK_BH
config INLINE_SPIN_LOCK_IRQ
def_bool y
depends on !GENERIC_LOCKBREAK && ARCH_INLINE_SPIN_LOCK_IRQ
config INLINE_SPIN_LOCK_IRQSAVE
def_bool y
depends on !GENERIC_LOCKBREAK && ARCH_INLINE_SPIN_LOCK_IRQSAVE
config INLINE_SPIN_UNLOCK_BH
def_bool y
depends on ARCH_INLINE_SPIN_UNLOCK_BH
config INLINE_SPIN_UNLOCK_IRQ
def_bool y
depends on !PREEMPT || ARCH_INLINE_SPIN_UNLOCK_IRQ
config INLINE_SPIN_UNLOCK_IRQRESTORE
def_bool y
depends on ARCH_INLINE_SPIN_UNLOCK_IRQRESTORE
config INLINE_READ_TRYLOCK
def_bool y
depends on ARCH_INLINE_READ_TRYLOCK
config INLINE_READ_LOCK
def_bool y
depends on !GENERIC_LOCKBREAK && ARCH_INLINE_READ_LOCK
config INLINE_READ_LOCK_BH
def_bool y
depends on !GENERIC_LOCKBREAK && ARCH_INLINE_READ_LOCK_BH
config INLINE_READ_LOCK_IRQ
def_bool y
depends on !GENERIC_LOCKBREAK && ARCH_INLINE_READ_LOCK_IRQ
config INLINE_READ_LOCK_IRQSAVE
def_bool y
depends on !GENERIC_LOCKBREAK && ARCH_INLINE_READ_LOCK_IRQSAVE
config INLINE_READ_UNLOCK
def_bool y
depends on !PREEMPT || ARCH_INLINE_READ_UNLOCK
config INLINE_READ_UNLOCK_BH
def_bool y
depends on ARCH_INLINE_READ_UNLOCK_BH
config INLINE_READ_UNLOCK_IRQ
def_bool y
depends on !PREEMPT || ARCH_INLINE_READ_UNLOCK_IRQ
config INLINE_READ_UNLOCK_IRQRESTORE
def_bool y
depends on ARCH_INLINE_READ_UNLOCK_IRQRESTORE
config INLINE_WRITE_TRYLOCK
def_bool y
depends on ARCH_INLINE_WRITE_TRYLOCK
config INLINE_WRITE_LOCK
def_bool y
depends on !GENERIC_LOCKBREAK && ARCH_INLINE_WRITE_LOCK
config INLINE_WRITE_LOCK_BH
def_bool y
depends on !GENERIC_LOCKBREAK && ARCH_INLINE_WRITE_LOCK_BH
config INLINE_WRITE_LOCK_IRQ
def_bool y
depends on !GENERIC_LOCKBREAK && ARCH_INLINE_WRITE_LOCK_IRQ
config INLINE_WRITE_LOCK_IRQSAVE
def_bool y
depends on !GENERIC_LOCKBREAK && ARCH_INLINE_WRITE_LOCK_IRQSAVE
config INLINE_WRITE_UNLOCK
def_bool y
depends on !PREEMPT || ARCH_INLINE_WRITE_UNLOCK
config INLINE_WRITE_UNLOCK_BH
def_bool y
depends on ARCH_INLINE_WRITE_UNLOCK_BH
config INLINE_WRITE_UNLOCK_IRQ
def_bool y
depends on !PREEMPT || ARCH_INLINE_WRITE_UNLOCK_IRQ
config INLINE_WRITE_UNLOCK_IRQRESTORE
def_bool y
depends on ARCH_INLINE_WRITE_UNLOCK_IRQRESTORE
endif
config MUTEX_SPIN_ON_OWNER
def_bool y
depends on SMP && !DEBUG_MUTEXES
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