Buildresult: linus/x86_64-allnoconfig/x86_64-gcc4.6 built on Jul 18 2018, 11:01

kisskb

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Status:	OK
Date/Time:	Jul 18 2018, 11:01
Duration:	0:00:18.219942
Builder:	ka4
Revision:	Mark HI and TASKLET softirq synchronous (`3c53776e29f81719efcf8f7a6e30cdf753bee94d)`
Target:	linus/x86_64-allnoconfig/x86_64-gcc4.6
Branch:	linus
Compiler:	x86_64-gcc4.6 (x86_64-linux-gcc (GCC) 4.6.3)
Config:	allnoconfig (download)
Log:	Download original Possible warnings (3) arch/x86/kernel/apic/io_apic.c:1033:6: warning: 'irq' may be used uninitialized in this function [-Wuninitialized] kernel/printk/printk.c:183:16: warning: 'old' may be used uninitialized in this function [-Wuninitialized] arch/x86/kernel/e820.c:651:16: warning: 'gapstart' may be used uninitialized in this function [-Wuninitialized] Full Log # git rev-parse -q --verify 3c53776e29f81719efcf8f7a6e30cdf753bee94d^{commit} 3c53776e29f81719efcf8f7a6e30cdf753bee94d already have revision, skipping fetch # git checkout -q -f -B kisskb 3c53776e29f81719efcf8f7a6e30cdf753bee94d # git clean -qxdf # < git log -1 # commit 3c53776e29f81719efcf8f7a6e30cdf753bee94d # Author: Linus Torvalds <torvalds@linux-foundation.org> # Date: Mon Jan 8 11:51:04 2018 -0800 # # Mark HI and TASKLET softirq synchronous # # Way back in 4.9, we committed 4cd13c21b207 ("softirq: Let ksoftirqd do # its job"), and ever since we've had small nagging issues with it. For # example, we've had: # # 1ff688209e2e ("watchdog: core: make sure the watchdog_worker is not deferred") # 8d5755b3f77b ("watchdog: softdog: fire watchdog even if softirqs do not get to run") # 217f69743681 ("net: busy-poll: allow preemption in sk_busy_loop()") # # all of which worked around some of the effects of that commit. # # The DVB people have also complained that the commit causes excessive USB # URB latencies, which seems to be due to the USB code using tasklets to # schedule USB traffic. This seems to be an issue mainly when already # living on the edge, but waiting for ksoftirqd to handle it really does # seem to cause excessive latencies. # # Now Hanna Hawa reports that this issue isn't just limited to USB URB and # DVB, but also causes timeout problems for the Marvell SoC team: # # "I'm facing kernel panic issue while running raid 5 on sata disks # connected to Macchiatobin (Marvell community board with Armada-8040 # SoC with 4 ARMv8 cores of CA72) Raid 5 built with Marvell DMA engine # and async_tx mechanism (ASYNC_TX_DMA [=y]); the DMA driver (mv_xor_v2) # uses a tasklet to clean the done descriptors from the queue" # # The latency problem causes a panic: # # mv_xor_v2 f0400000.xor: dma_sync_wait: timeout! # Kernel panic - not syncing: async_tx_quiesce: DMA error waiting for transaction # # We've discussed simply just reverting the original commit entirely, and # also much more involved solutions (with per-softirq threads etc). This # patch is intentionally stupid and fairly limited, because the issue # still remains, and the other solutions either got sidetracked or had # other issues. # # We should probably also consider the timer softirqs to be synchronous # and not be delayed to ksoftirqd (since they were the issue with the # earlier watchdog problems), but that should be done as a separate patch. # This does only the tasklet cases. # # Reported-and-tested-by: Hanna Hawa <hannah@marvell.com> # Reported-and-tested-by: Josef Griebichler <griebichler.josef@gmx.at> # Reported-by: Mauro Carvalho Chehab <mchehab@s-opensource.com> # Cc: Alan Stern <stern@rowland.harvard.edu> # Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> # Cc: Eric Dumazet <edumazet@google.com> # Cc: Ingo Molnar <mingo@kernel.org> # Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> # < /opt/cross/kisskb/gcc-4.6.3-nolibc/x86_64-linux/bin/x86_64-linux-gcc --version # < git log --format=%s --max-count=1 3c53776e29f81719efcf8f7a6e30cdf753bee94d # < make -s -j 10 ARCH=x86_64 O=/kisskb/build/linus_x86_64-allnoconfig_x86_64 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/x86_64-linux/bin/x86_64-linux- allnoconfig # make -s -j 10 ARCH=x86_64 O=/kisskb/build/linus_x86_64-allnoconfig_x86_64 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/x86_64-linux/bin/x86_64-linux- /kisskb/src/arch/x86/kernel/apic/io_apic.c: In function 'mp_map_pin_to_irq': /kisskb/src/arch/x86/kernel/apic/io_apic.c:1033:6: warning: 'irq' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/kernel/printk/printk.c: In function 'devkmsg_sysctl_set_loglvl': /kisskb/src/kernel/printk/printk.c:183:16: warning: 'old' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/arch/x86/kernel/e820.c: In function 'e820__setup_pci_gap': /kisskb/src/arch/x86/kernel/e820.c:651:16: warning: 'gapstart' may be used uninitialized in this function [-Wuninitialized] Completed OK # rm -rf /kisskb/build/linus_x86_64-allnoconfig_x86_64 # Build took: 0:00:18.219942

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