Buildresult: powerpc-next/ps3_defconfig/powerpc-gcc4.6 built on Apr 4 2018, 22:27
kisskb
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Status:
OK
Date/Time:
Apr 4 2018, 22:27
Duration:
0:01:04.298807
Builder:
ka2
Revision:
cxl: Fix possible deadlock when processing page faults from cxllib (
ad7b4e8022b9864c075fe71e1328b1d25cad82f6)
Target:
powerpc-next/ps3_defconfig/powerpc-gcc4.6
Branch:
powerpc-next
Compiler:
powerpc-gcc4.6
(powerpc-linux-gcc (GCC) 4.6.3)
Config:
ps3_defconfig
(
download
)
Log:
Download original
Possible warnings (13)
ipc/shm.c:1565:59: warning: 'file' may be used uninitialized in this function [-Wuninitialized] kernel/printk/printk.c:183:16: warning: 'old' may be used uninitialized in this function [-Wuninitialized] kernel/rcu/srcutree.c:146:32: warning: 'levelspread[<U1140>]' may be used uninitialized in this function [-Wuninitialized] net/core/gen_stats.c:149:19: warning: 'seq' may be used uninitialized in this function [-Wuninitialized] lib/rhashtable.c:269:2: warning: 'next' may be used uninitialized in this function [-Wuninitialized] net/core/flow_dissector.c:789:7: warning: 'vlan' may be used uninitialized in this function [-Wuninitialized] net/core/dev.c:3149:15: warning: 'tail' may be used uninitialized in this function [-Wuninitialized] lib/mpi/mpicoder.c:352:8: warning: 'buff' may be used uninitialized in this function [-Wuninitialized] net/mac80211/tx.c:2452:27: warning: 'chanctx_conf' may be used uninitialized in this function [-Wuninitialized] net/bluetooth/hidp/core.c:1378:18: warning: 'session' may be used uninitialized in this function [-Wuninitialized] net/mac80211/mlme.c:1350:3: warning: 'pwr_level_cisco' may be used uninitialized in this function [-Wuninitialized] fs/udf/unicode.c:157:15: warning: 'c' may be used uninitialized in this function [-Wuninitialized] WARNING: modpost: Found 2 section mismatch(es).
Full Log
# git rev-parse -q --verify ad7b4e8022b9864c075fe71e1328b1d25cad82f6^{commit} ad7b4e8022b9864c075fe71e1328b1d25cad82f6 already have revision, skipping fetch # git checkout -q -f -B kisskb ad7b4e8022b9864c075fe71e1328b1d25cad82f6 # git clean -qxdf # < git log -1 # commit ad7b4e8022b9864c075fe71e1328b1d25cad82f6 # Author: Frederic Barrat <fbarrat@linux.vnet.ibm.com> # Date: Tue Apr 3 15:54:02 2018 +0200 # # cxl: Fix possible deadlock when processing page faults from cxllib # # cxllib_handle_fault() is called by an external driver when it needs to # have the host resolve page faults for a buffer. The buffer can cover # several pages and VMAs. The function iterates over all the pages used # by the buffer, based on the page size of the VMA. # # To ensure some stability while processing the faults, the thread T1 # grabs the mm->mmap_sem semaphore with read access (R1). However, when # processing a page fault for a single page, one of the underlying # functions, copro_handle_mm_fault(), also grabs the same semaphore with # read access (R2). So the thread T1 takes the semaphore twice. # # If another thread T2 tries to access the semaphore in write mode W1 # (say, because it wants to allocate memory and calls 'brk'), then that # thread T2 will have to wait because there's a reader (R1). If the # thread T1 is processing a new page at that time, it won't get an # automatic grant at R2, because there's now a writer thread # waiting (T2). And we have a deadlock. # # The timeline is: # 1. thread T1 owns the semaphore with read access R1 # 2. thread T2 requests write access W1 and waits # 3. thread T1 requests read access R2 and waits # # The fix is for the thread T1 to release the semaphore R1 once it got # the information it needs from the current VMA. The address space/VMAs # could evolve while T1 iterates over the full buffer, but in the # unlikely case where T1 misses a page, the external driver will raise a # new page fault when retrying the memory access. # # Fixes: 3ced8d730063 ("cxl: Export library to support IBM XSL") # Cc: stable@vger.kernel.org # 4.13+ # Signed-off-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com> # Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> # < /opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux-gcc --version # < git log --format=%s --max-count=1 ad7b4e8022b9864c075fe71e1328b1d25cad82f6 # < make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-next_ps3_defconfig_powerpc CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux- ps3_defconfig # make -s -j 48 ARCH=powerpc O=/kisskb/build/powerpc-next_ps3_defconfig_powerpc CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux- /kisskb/src/ipc/shm.c: In function 'SyS_shmdt': /kisskb/src/ipc/shm.c:1565:59: warning: 'file' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/ipc/shm.c:1487:15: note: 'file' was declared here /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/kernel/rcu/srcutree.c: In function 'init_srcu_struct_fields': /kisskb/src/kernel/rcu/srcutree.c:146:32: warning: 'levelspread[<U1140>]' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/kernel/rcu/srcutree.c:94:6: note: 'levelspread[<U1140>]' was declared here /kisskb/src/net/core/gen_stats.c: In function '__gnet_stats_copy_basic': /kisskb/src/net/core/gen_stats.c:149:19: warning: 'seq' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/lib/rhashtable.c: In function 'rht_deferred_worker': /kisskb/src/lib/rhashtable.c:269:2: warning: 'next' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/lib/rhashtable.c:234:28: note: 'next' was declared here /kisskb/src/net/core/flow_dissector.c: In function '__skb_flow_dissect': /kisskb/src/net/core/flow_dissector.c:789:7: warning: 'vlan' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/net/core/dev.c: In function 'validate_xmit_skb_list': /kisskb/src/net/core/dev.c:3149:15: warning: 'tail' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/lib/mpi/mpicoder.c: In function 'mpi_read_raw_from_sgl': /kisskb/src/lib/mpi/mpicoder.c:352:8: warning: 'buff' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/net/mac80211/tx.c: In function 'ieee80211_build_hdr': /kisskb/src/net/mac80211/tx.c:2452:27: warning: 'chanctx_conf' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/net/bluetooth/hidp/core.c: In function 'hidp_connection_add': /kisskb/src/net/bluetooth/hidp/core.c:1378:18: warning: 'session' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/net/mac80211/mlme.c: In function 'ieee80211_rx_mgmt_beacon': /kisskb/src/net/mac80211/mlme.c:1350:3: warning: 'pwr_level_cisco' may be used uninitialized in this function [-Wuninitialized] /kisskb/src/net/mac80211/mlme.c:1307:6: note: 'pwr_level_cisco' was declared here /kisskb/src/fs/udf/unicode.c: In function 'udf_name_conv_char': /kisskb/src/fs/udf/unicode.c:157:15: warning: 'c' may be used uninitialized in this function [-Wuninitialized] WARNING: modpost: Found 2 section mismatch(es). To see full details build your kernel with: 'make CONFIG_DEBUG_SECTION_MISMATCH=y' Completed OK # rm -rf /kisskb/build/powerpc-next_ps3_defconfig_powerpc # Build took: 0:01:04.298807
© Michael Ellerman 2006-2018.