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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Kbuild | -rw-r--r-- | 0 bytes |
atmel_lcdc.h | -rw-r--r-- | 6.8 KB |
aty128.h | -rw-r--r-- | 13.2 KB |
auo_k190xfb.h | -rw-r--r-- | 2.8 KB |
broadsheetfb.h | -rw-r--r-- | 2.1 KB |
cirrus.h | -rw-r--r-- | 5.7 KB |
cvisionppc.h | -rw-r--r-- | 1.5 KB |
da8xx-fb.h | -rw-r--r-- | 2.0 KB |
display_timing.h | -rw-r--r-- | 3.0 KB |
edid.h | -rw-r--r-- | 189 bytes |
exynos_mipi_dsim.h | -rw-r--r-- | 12.2 KB |
gbe.h | -rw-r--r-- | 10.5 KB |
hecubafb.h | -rw-r--r-- | 1.5 KB |
iga.h | -rw-r--r-- | 787 bytes |
ili9320.h | -rw-r--r-- | 5.8 KB |
kyro.h | -rw-r--r-- | 2.4 KB |
mach64.h | -rw-r--r-- | 47.1 KB |
maxinefb.h | -rw-r--r-- | 1.2 KB |
mbxfb.h | -rw-r--r-- | 2.1 KB |
metronomefb.h | -rw-r--r-- | 1.5 KB |
mipi_display.h | -rw-r--r-- | 4.1 KB |
mmp_disp.h | -rw-r--r-- | 7.6 KB |
neomagic.h | -rw-r--r-- | 4.9 KB |
newport.h | -rw-r--r-- | 18.6 KB |
of_display_timing.h | -rw-r--r-- | 552 bytes |
of_videomode.h | -rw-r--r-- | 367 bytes |
omap-panel-data.h | -rw-r--r-- | 6.1 KB |
omapdss.h | -rw-r--r-- | 29.7 KB |
omapvrfb.h | -rw-r--r-- | 2.4 KB |
permedia2.h | -rw-r--r-- | 9.0 KB |
platform_lcd.h | -rw-r--r-- | 589 bytes |
pm3fb.h | -rw-r--r-- | 45.3 KB |
pmag-ba-fb.h | -rw-r--r-- | 1.0 KB |
pmagb-b-fb.h | -rw-r--r-- | 2.3 KB |
pxa168fb.h | -rw-r--r-- | 2.7 KB |
radeon.h | -rw-r--r-- | 109.2 KB |
s1d13xxxfb.h | -rw-r--r-- | 9.9 KB |
sa1100fb.h | -rw-r--r-- | 1.3 KB |
samsung_fimd.h | -rw-r--r-- | 16.4 KB |
sh_mipi_dsi.h | -rw-r--r-- | 1.4 KB |
sh_mobile_hdmi.h | -rw-r--r-- | 1.2 KB |
sh_mobile_lcdc.h | -rw-r--r-- | 6.1 KB |
sh_mobile_meram.h | -rw-r--r-- | 2.4 KB |
sisfb.h | -rw-r--r-- | 1.2 KB |
sstfb.h | -rw-r--r-- | 11.0 KB |
tdfx.h | -rw-r--r-- | 5.3 KB |
tgafb.h | -rw-r--r-- | 6.9 KB |
trident.h | -rw-r--r-- | 3.2 KB |
udlfb.h | -rw-r--r-- | 2.8 KB |
uvesafb.h | -rw-r--r-- | 2.8 KB |
vga.h | -rw-r--r-- | 13.7 KB |
videomode.h | -rw-r--r-- | 1.3 KB |
w100fb.h | -rw-r--r-- | 3.7 KB |
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