[PATCH 3.13.y-ckt 38/78] vfs: Make sendfile(2) killable even better

From	Kamal Mostafa <kamal@canonical.com>
Newsgroups	linux.kernel
Subject	[PATCH 3.13.y-ckt 38/78] vfs: Make sendfile(2) killable even better
Date	2015-12-17 01:50 +0100
Message-ID	<qGuVC-Ae-49@gated-at.bofh.it> (permalink)
References	<qGuVA-Ae-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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3.13.11-ckt32 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jan Kara <jack@suse.cz>

commit c725bfce7968009756ed2836a8cd7ba4dc163011 upstream.

Commit 296291cdd162 (mm: make sendfile(2) killable) fixed an issue where
sendfile(2) was doing a lot of tiny writes into a filesystem and thus
was unkillable for a long time. However sendfile(2) can be (mis)used to
issue lots of writes into arbitrary file descriptor such as evenfd or
similar special file descriptors which never hit the standard filesystem
write path and thus are still unkillable. E.g. the following example
from Dmitry burns CPU for ~16s on my test system without possibility to
be killed:

        int r1 = eventfd(0, 0);
        int r2 = memfd_create("", 0);
        unsigned long n = 1<<30;
        fallocate(r2, 0, 0, n);
        sendfile(r1, r2, 0, n);

There are actually quite a few tests for pending signals in sendfile
code however we data to write is always available none of them seems to
trigger. So fix the problem by adding a test for pending signal into
splice_from_pipe_next() also before the loop waiting for pipe buffers to
be available. This should fix all the lockup issues with sendfile of the
do-ton-of-tiny-writes nature.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 fs/splice.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/splice.c b/fs/splice.c
index f345d53..4eef647 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -871,6 +871,13 @@ EXPORT_SYMBOL(splice_from_pipe_feed);
  */
 int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd)
 {
+	/*
+	 * Check for signal early to make process killable when there are
+	 * always buffers available
+	 */
+	if (signal_pending(current))
+		return -ERESTARTSYS;
+
 	while (!pipe->nrbufs) {
 		if (!pipe->writers)
 			return 0;
-- 
1.9.1

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Thread

[3.13.y-ckt stable] Linux 3.13.11-ckt32 stable review Kamal Mostafa <kamal@canonical.com> - 2015-12-17 01:50 +0100
  [PATCH 3.13.y-ckt 38/78] vfs: Make sendfile(2) killable even better Kamal Mostafa <kamal@canonical.com> - 2015-12-17 01:50 +0100
  [PATCH 3.13.y-ckt 56/78] sched/core: Clear the root_domain cpumasks in init_rootdomain() Kamal Mostafa <kamal@canonical.com> - 2015-12-17 01:50 +0100
  [PATCH 3.13.y-ckt 72/78] packet: only allow extra vlan len on ethernet devices Kamal Mostafa <kamal@canonical.com> - 2015-12-17 01:50 +0100
  [PATCH 3.13.y-ckt 62/78] tcp: md5: fix lockdep annotation Kamal Mostafa <kamal@canonical.com> - 2015-12-17 01:50 +0100
  [PATCH 3.13.y-ckt 63/78] ARM: dts: Kirkwood: Fix QNAP TS219 power-off Kamal Mostafa <kamal@canonical.com> - 2015-12-17 01:50 +0100
  [PATCH 3.13.y-ckt 47/78] drm/radeon: make some dpm errors debug only Kamal Mostafa <kamal@canonical.com> - 2015-12-17 01:50 +0100
  [PATCH 3.13.y-ckt 04/78] iio: lpc32xx_adc: fix warnings caused by enabling unprepared clock Kamal Mostafa <kamal@canonical.com> - 2015-12-17 01:50 +0100
  [PATCH 3.13.y-ckt 27/78] USB: option: add XS Stick W100-2 from 4G Systems Kamal Mostafa <kamal@canonical.com> - 2015-12-17 01:50 +0100
  [PATCH 3.13.y-ckt 68/78] net: mvneta: fix bit assignment for RX packet irq enable Kamal Mostafa <kamal@canonical.com> - 2015-12-17 01:50 +0100
  [PATCH 3.13.y-ckt 75/78] net: ip6mr: fix static mfc/dev leaks on table destruction Kamal Mostafa <kamal@canonical.com> - 2015-12-17 01:50 +0100
  [PATCH 3.13.y-ckt 08/78] x86/fpu: Fix 32-bit signal frame handling Kamal Mostafa <kamal@canonical.com> - 2015-12-17 01:50 +0100
  [PATCH 3.13.y-ckt 64/78] isdn: Partially revert debug format string usage clean up Kamal Mostafa <kamal@canonical.com> - 2015-12-17 01:50 +0100
  [PATCH 3.13.y-ckt 65/78] remoteproc: avoid stack overflow in debugfs file Kamal Mostafa <kamal@canonical.com> - 2015-12-17 01:50 +0100
  [PATCH 3.13.y-ckt 76/78] unix: avoid use-after-free in ep_remove_wait_queue Kamal Mostafa <kamal@canonical.com> - 2015-12-17 01:50 +0100
  [PATCH 3.13.y-ckt 35/78] powerpc/tm: Block signal return setting invalid MSR state Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:00 +0100
  [PATCH 3.13.y-ckt 58/78] mmc: remove bondage between REQ_META and reliable write Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:00 +0100
  [PATCH 3.13.y-ckt 55/78] wan/x25: Fix use-after-free in x25_asy_open_tty() Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:00 +0100
  [PATCH 3.13.y-ckt 45/78] RDS: fix race condition when sending a message on unbound socket Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:00 +0100
  [PATCH 3.13.y-ckt 46/78] btrfs: fix signed overflows in btrfs_sync_file Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:00 +0100
  [PATCH 3.13.y-ckt 37/78] fix sysvfs symlinks Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:00 +0100
  [PATCH 3.13.y-ckt 51/78] target: Fix race for SCF_COMPARE_AND_WRITE_POST checking Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:00 +0100
  [PATCH 3.13.y-ckt 48/78] nfs: if we have no valid attrs, then don't declare the attribute cache valid Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:00 +0100
  [PATCH 3.13.y-ckt 49/78] xen/gntdev: Grant maps should not be subject to NUMA balancing Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:00 +0100
  [PATCH 3.13.y-ckt 54/78] Fix a memory leak in scsi_host_dev_release() Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:00 +0100
  [PATCH 3.13.y-ckt 57/78] x86/signal: Fix restart_syscall number for x32 tasks Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:00 +0100
  [PATCH 3.13.y-ckt 43/78] arm64: KVM: Fix AArch32 to AArch64 register mapping Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:00 +0100
  [PATCH 3.13.y-ckt 50/78] iscsi-target: Fix rx_login_comp hang after login failure Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:00 +0100
  [PATCH 3.13.y-ckt 60/78] usb: musb: core: fix order of arguments to ulpi write callback Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:00 +0100
  [PATCH 3.13.y-ckt 53/78] block: Always check queue limits for cloned requests Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:00 +0100
  [PATCH 3.13.y-ckt 03/78] stackprotector: Introduce CONFIG_CC_STACKPROTECTOR_STRONG Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:00 +0100
  [PATCH 3.13.y-ckt 59/78] sctp: translate host order to network order when setting a hmacid Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:00 +0100
  [PATCH 3.13.y-ckt 52/78] target: fix COMPARE_AND_WRITE non zero SGL offset data corruption Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:00 +0100
  [PATCH 3.13.y-ckt 36/78] ARC: dw2 unwind: Remove falllback linear search thru FDE entries Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 31/78] fat: fix fake_offset handling on error path Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 42/78] ring-buffer: Update read stamp with first real commit on page Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 15/78] mac80211: mesh: fix call_rcu() usage Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 44/78] drm/radeon: make rv770_set_sw_state failures non-fatal Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 30/78] ALSA: hda - Apply HP headphone fixups more generically Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 33/78] parisc: Drop unused MADV_xxxK_PAGES flags from asm/mman.h Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 19/78] MIPS: KVM: Fix ASID restoration logic Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 23/78] xhci: Fix a race in usb2 LPM resume, blocking U3 for usb2 devices Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 32/78] kernel/signal.c: unexport sigsuspend() Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 21/78] MIPS: KVM: Uninit VCPU in vcpu_create error path Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 12/78] USB: serial: option: add support for Novatel MiFi USB620L Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 22/78] xhci: Workaround to get Intel xHCI reset working more reliably Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 16/78] usb: dwc3: gadget: let us set lower max_speed Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 40/78] nfs4: start callback_ident at idr 1 Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 14/78] ASoC: wm8962: correct addresses for HPF_C_0/1 Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 41/78] ALSA: hda - Fix headphone noise after Dell XPS 13 resume back from S3 Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 13/78] USB: ti_usb_3410_5052: Add Honeywell HGI80 ID Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 28/78] usblp: do not set TASK_INTERRUPTIBLE before lock Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 20/78] MIPS: KVM: Fix CACHE immediate offset sign extension Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 39/78] vfs: Avoid softlockups with sendfile(2) Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 25/78] ALSA: hda - Add fixup for Acer Aspire One Cloudbook 14 Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 29/78] mac: validate mac_partition is within sector Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 24/78] x86/cpu: Fix SMAP check in PVOPS environments Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 26/78] arm64: restore bogomips information in /proc/cpuinfo Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:10 +0100
  [PATCH 3.13.y-ckt 05/78] iio:ad5064: Make sure ad5064_i2c_write() returns 0 on success Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:20 +0100
  [PATCH 3.13.y-ckt 10/78] ALSA: usb-audio: prevent CH345 multiport output SysEx corruption Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:20 +0100
  [PATCH 3.13.y-ckt 11/78] ALSA: usb-audio: work around CH345 input SysEx corruption Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:20 +0100
  [PATCH 3.13.y-ckt 07/78] iio:ad7793: Fix ad7785 product ID Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:20 +0100
  [PATCH 3.13.y-ckt 01/78] tty: fix stall caused by missing memory barrier in drivers/tty/n_tty.c Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:20 +0100
  [PATCH 3.13.y-ckt 09/78] ALSA: usb-audio: add packet size quirk for the Medeli DD305 Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:20 +0100
  [PATCH 3.13.y-ckt 06/78] iio: ad5064: Fix ad5629/ad5669 shift Kamal Mostafa <kamal@canonical.com> - 2015-12-17 02:20 +0100

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