Revision 50338b889dc504c69e0cb316ac92d1b9e51f3c8a authored by Török Edwin on 15 June 2011, 21:06:14 UTC, committed by Al Viro on 16 June 2011, 15:27:39 UTC
Git bisection shows that commit e6bc45d65df8599fdbae73be9cec4ceed274db53 causes BUG_ONs under high I/O load: kernel BUG at fs/inode.c:1368! [ 2862.501007] Call Trace: [ 2862.501007] [<ffffffff811691d8>] d_kill+0xf8/0x140 [ 2862.501007] [<ffffffff81169c19>] dput+0xc9/0x190 [ 2862.501007] [<ffffffff8115577f>] fput+0x15f/0x210 [ 2862.501007] [<ffffffff81152171>] filp_close+0x61/0x90 [ 2862.501007] [<ffffffff81152251>] sys_close+0xb1/0x110 [ 2862.501007] [<ffffffff814c14fb>] system_call_fastpath+0x16/0x1b A reliable way to reproduce this bug is: Login to KDE, run 'rsnapshot sync', and apt-get install openjdk-6-jdk, and apt-get remove openjdk-6-jdk. The buggy part of the patch is this: struct inode *inode = NULL; ..... - if (nd.last.name[nd.last.len]) - goto slashes; inode = dentry->d_inode; - if (inode) - ihold(inode); + if (nd.last.name[nd.last.len] || !inode) + goto slashes; + ihold(inode) ... if (inode) iput(inode); /* truncate the inode here */ If nd.last.name[nd.last.len] is nonzero (and thus goto slashes branch is taken), and dentry->d_inode is non-NULL, then this code now does an additional iput on the inode, which is wrong. Fix this by only setting the inode variable if nd.last.name[nd.last.len] is 0. Reference: https://lkml.org/lkml/2011/6/15/50 Reported-by: Norbert Preining <preining@logic.at> Reported-by: Török Edwin <edwintorok@gmail.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Török Edwin <edwintorok@gmail.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Kbuild
#
# Kbuild for top-level directory of the kernel
# This file takes care of the following:
# 1) Generate bounds.h
# 2) Generate asm-offsets.h (may need bounds.h)
# 3) Check for missing system calls
#####
# 1) Generate bounds.h
bounds-file := include/generated/bounds.h
always := $(bounds-file)
targets := $(bounds-file) kernel/bounds.s
quiet_cmd_bounds = GEN $@
define cmd_bounds
(set -e; \
echo "#ifndef __LINUX_BOUNDS_H__"; \
echo "#define __LINUX_BOUNDS_H__"; \
echo "/*"; \
echo " * DO NOT MODIFY."; \
echo " *"; \
echo " * This file was generated by Kbuild"; \
echo " *"; \
echo " */"; \
echo ""; \
sed -ne $(sed-y) $<; \
echo ""; \
echo "#endif" ) > $@
endef
# We use internal kbuild rules to avoid the "is up to date" message from make
kernel/bounds.s: kernel/bounds.c FORCE
$(Q)mkdir -p $(dir $@)
$(call if_changed_dep,cc_s_c)
$(obj)/$(bounds-file): kernel/bounds.s Kbuild
$(Q)mkdir -p $(dir $@)
$(call cmd,bounds)
#####
# 2) Generate asm-offsets.h
#
offsets-file := include/generated/asm-offsets.h
always += $(offsets-file)
targets += $(offsets-file)
targets += arch/$(SRCARCH)/kernel/asm-offsets.s
# Default sed regexp - multiline due to syntax constraints
define sed-y
"/^->/{s:->#\(.*\):/* \1 */:; \
s:^->\([^ ]*\) [\$$#]*\([-0-9]*\) \(.*\):#define \1 \2 /* \3 */:; \
s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; \
s:->::; p;}"
endef
quiet_cmd_offsets = GEN $@
define cmd_offsets
(set -e; \
echo "#ifndef __ASM_OFFSETS_H__"; \
echo "#define __ASM_OFFSETS_H__"; \
echo "/*"; \
echo " * DO NOT MODIFY."; \
echo " *"; \
echo " * This file was generated by Kbuild"; \
echo " *"; \
echo " */"; \
echo ""; \
sed -ne $(sed-y) $<; \
echo ""; \
echo "#endif" ) > $@
endef
# We use internal kbuild rules to avoid the "is up to date" message from make
arch/$(SRCARCH)/kernel/asm-offsets.s: arch/$(SRCARCH)/kernel/asm-offsets.c \
$(obj)/$(bounds-file) FORCE
$(Q)mkdir -p $(dir $@)
$(call if_changed_dep,cc_s_c)
$(obj)/$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s Kbuild
$(call cmd,offsets)
#####
# 3) Check for missing system calls
#
quiet_cmd_syscalls = CALL $<
cmd_syscalls = $(CONFIG_SHELL) $< $(CC) $(c_flags)
PHONY += missing-syscalls
missing-syscalls: scripts/checksyscalls.sh FORCE
$(call cmd,syscalls)
# Keep these two files during make clean
no-clean-files := $(bounds-file) $(offsets-file)
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