January 2019 - Linux-stable-mirror

FAILED: patch "[PATCH] powerpc/tm: Unset MSR[TS] if not recheckpointing" failed to apply to 4.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 6f5b9f018f4c7686fd944d920209d1382d320e4e Mon Sep 17 00:00:00 2001 From: Breno Leitao <leitao(a)debian.org> Date: Mon, 26 Nov 2018 18:12:00 -0200 Subject: [PATCH] powerpc/tm: Unset MSR[TS] if not recheckpointing MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit There is a TM Bad Thing bug that can be caused when you return from a signal context in a suspended transaction but with ucontext MSR[TS] unset. This forces regs->msr[TS] to be set at syscall entrance (since the CPU state is transactional). It also calls treclaim() to flush the transaction state, which is done based on the live (mfmsr) MSR state. Since user context MSR[TS] is not set, then restore_tm_sigcontexts() is not called, thus, not executing recheckpoint, keeping the CPU state as not transactional. When calling rfid, SRR1 will have MSR[TS] set, but the CPU state is non transactional, causing the TM Bad Thing with the following stack: [ 33.862316] Bad kernel stack pointer 3fffd9dce3e0 at c00000000000c47c cpu 0x8: Vector: 700 (Program Check) at [c00000003ff7fd40] pc: c00000000000c47c: fast_exception_return+0xac/0xb4 lr: 00003fff865f442c sp: 3fffd9dce3e0 msr: 8000000102a03031 current = 0xc00000041f68b700 paca = 0xc00000000fb84800 softe: 0 irq_happened: 0x01 pid = 1721, comm = tm-signal-sigre Linux version 4.9.0-3-powerpc64le (debian-kernel(a)lists.debian.org) (gcc version 6.3.0 20170516 (Debian 6.3.0-18) ) #1 SMP Debian 4.9.30-2+deb9u2 (2017-06-26) WARNING: exception is not recoverable, can't continue The same problem happens on 32-bits signal handler, and the fix is very similar, if tm_recheckpoint() is not executed, then regs->msr[TS] should be zeroed. This patch also fixes a sparse warning related to lack of indentation when CONFIG_PPC_TRANSACTIONAL_MEM is set. Fixes: 2b0a576d15e0e ("powerpc: Add new transactional memory state to the signal context") CC: Stable <stable(a)vger.kernel.org> # 3.10+ Signed-off-by: Breno Leitao <leitao(a)debian.org> Tested-by: Michal Suchánek <msuchanek(a)suse.de> Signed-off-by: Michael Ellerman <mpe(a)ellerman.id.au> diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c index 7484f43493d3..2d47cc79e5b3 100644 --- a/arch/powerpc/kernel/signal_32.c +++ b/arch/powerpc/kernel/signal_32.c @@ -1158,11 +1158,11 @@ SYSCALL_DEFINE0(rt_sigreturn) { struct rt_sigframe __user *rt_sf; struct pt_regs *regs = current_pt_regs(); + int tm_restore = 0; #ifdef CONFIG_PPC_TRANSACTIONAL_MEM struct ucontext __user *uc_transact; unsigned long msr_hi; unsigned long tmp; - int tm_restore = 0; #endif /* Always make any pending restarted system calls return -EINTR */ current->restart_block.fn = do_no_restart_syscall; @@ -1210,11 +1210,19 @@ SYSCALL_DEFINE0(rt_sigreturn) goto bad; } } - if (!tm_restore) - /* Fall through, for non-TM restore */ + if (!tm_restore) { + /* + * Unset regs->msr because ucontext MSR TS is not + * set, and recheckpoint was not called. This avoid + * hitting a TM Bad thing at RFID + */ + regs->msr &= ~MSR_TS_MASK; + } + /* Fall through, for non-TM restore */ #endif - if (do_setcontext(&rt_sf->uc, regs, 1)) - goto bad; + if (!tm_restore) + if (do_setcontext(&rt_sf->uc, regs, 1)) + goto bad; /* * It's not clear whether or why it is desirable to save the diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c index ba093ec5a21f..0935fe6c282a 100644 --- a/arch/powerpc/kernel/signal_64.c +++ b/arch/powerpc/kernel/signal_64.c @@ -757,11 +757,23 @@ SYSCALL_DEFINE0(rt_sigreturn) &uc_transact->uc_mcontext)) goto badframe; } - else - /* Fall through, for non-TM restore */ #endif - if (restore_sigcontext(current, NULL, 1, &uc->uc_mcontext)) - goto badframe; + /* Fall through, for non-TM restore */ + if (!MSR_TM_ACTIVE(msr)) { + /* + * Unset MSR[TS] on the thread regs since MSR from user + * context does not have MSR active, and recheckpoint was + * not called since restore_tm_sigcontexts() was not called + * also. + * + * If not unsetting it, the code can RFID to userspace with + * MSR[TS] set, but without CPU in the proper state, + * causing a TM bad thing. + */ + current->thread.regs->msr &= ~MSR_TS_MASK; + if (restore_sigcontext(current, NULL, 1, &uc->uc_mcontext)) + goto badframe; + } if (restore_altstack(&uc->uc_stack)) goto badframe;

5 years, 11 months

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FAILED: patch "[PATCH] powerpc/tm: Unset MSR[TS] if not recheckpointing" failed to apply to 4.9-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 6f5b9f018f4c7686fd944d920209d1382d320e4e Mon Sep 17 00:00:00 2001 From: Breno Leitao <leitao(a)debian.org> Date: Mon, 26 Nov 2018 18:12:00 -0200 Subject: [PATCH] powerpc/tm: Unset MSR[TS] if not recheckpointing MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit There is a TM Bad Thing bug that can be caused when you return from a signal context in a suspended transaction but with ucontext MSR[TS] unset. This forces regs->msr[TS] to be set at syscall entrance (since the CPU state is transactional). It also calls treclaim() to flush the transaction state, which is done based on the live (mfmsr) MSR state. Since user context MSR[TS] is not set, then restore_tm_sigcontexts() is not called, thus, not executing recheckpoint, keeping the CPU state as not transactional. When calling rfid, SRR1 will have MSR[TS] set, but the CPU state is non transactional, causing the TM Bad Thing with the following stack: [ 33.862316] Bad kernel stack pointer 3fffd9dce3e0 at c00000000000c47c cpu 0x8: Vector: 700 (Program Check) at [c00000003ff7fd40] pc: c00000000000c47c: fast_exception_return+0xac/0xb4 lr: 00003fff865f442c sp: 3fffd9dce3e0 msr: 8000000102a03031 current = 0xc00000041f68b700 paca = 0xc00000000fb84800 softe: 0 irq_happened: 0x01 pid = 1721, comm = tm-signal-sigre Linux version 4.9.0-3-powerpc64le (debian-kernel(a)lists.debian.org) (gcc version 6.3.0 20170516 (Debian 6.3.0-18) ) #1 SMP Debian 4.9.30-2+deb9u2 (2017-06-26) WARNING: exception is not recoverable, can't continue The same problem happens on 32-bits signal handler, and the fix is very similar, if tm_recheckpoint() is not executed, then regs->msr[TS] should be zeroed. This patch also fixes a sparse warning related to lack of indentation when CONFIG_PPC_TRANSACTIONAL_MEM is set. Fixes: 2b0a576d15e0e ("powerpc: Add new transactional memory state to the signal context") CC: Stable <stable(a)vger.kernel.org> # 3.10+ Signed-off-by: Breno Leitao <leitao(a)debian.org> Tested-by: Michal Suchánek <msuchanek(a)suse.de> Signed-off-by: Michael Ellerman <mpe(a)ellerman.id.au> diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c index 7484f43493d3..2d47cc79e5b3 100644 --- a/arch/powerpc/kernel/signal_32.c +++ b/arch/powerpc/kernel/signal_32.c @@ -1158,11 +1158,11 @@ SYSCALL_DEFINE0(rt_sigreturn) { struct rt_sigframe __user *rt_sf; struct pt_regs *regs = current_pt_regs(); + int tm_restore = 0; #ifdef CONFIG_PPC_TRANSACTIONAL_MEM struct ucontext __user *uc_transact; unsigned long msr_hi; unsigned long tmp; - int tm_restore = 0; #endif /* Always make any pending restarted system calls return -EINTR */ current->restart_block.fn = do_no_restart_syscall; @@ -1210,11 +1210,19 @@ SYSCALL_DEFINE0(rt_sigreturn) goto bad; } } - if (!tm_restore) - /* Fall through, for non-TM restore */ + if (!tm_restore) { + /* + * Unset regs->msr because ucontext MSR TS is not + * set, and recheckpoint was not called. This avoid + * hitting a TM Bad thing at RFID + */ + regs->msr &= ~MSR_TS_MASK; + } + /* Fall through, for non-TM restore */ #endif - if (do_setcontext(&rt_sf->uc, regs, 1)) - goto bad; + if (!tm_restore) + if (do_setcontext(&rt_sf->uc, regs, 1)) + goto bad; /* * It's not clear whether or why it is desirable to save the diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c index ba093ec5a21f..0935fe6c282a 100644 --- a/arch/powerpc/kernel/signal_64.c +++ b/arch/powerpc/kernel/signal_64.c @@ -757,11 +757,23 @@ SYSCALL_DEFINE0(rt_sigreturn) &uc_transact->uc_mcontext)) goto badframe; } - else - /* Fall through, for non-TM restore */ #endif - if (restore_sigcontext(current, NULL, 1, &uc->uc_mcontext)) - goto badframe; + /* Fall through, for non-TM restore */ + if (!MSR_TM_ACTIVE(msr)) { + /* + * Unset MSR[TS] on the thread regs since MSR from user + * context does not have MSR active, and recheckpoint was + * not called since restore_tm_sigcontexts() was not called + * also. + * + * If not unsetting it, the code can RFID to userspace with + * MSR[TS] set, but without CPU in the proper state, + * causing a TM bad thing. + */ + current->thread.regs->msr &= ~MSR_TS_MASK; + if (restore_sigcontext(current, NULL, 1, &uc->uc_mcontext)) + goto badframe; + } if (restore_altstack(&uc->uc_stack)) goto badframe;

5 years, 11 months

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FAILED: patch "[PATCH] powerpc/tm: Unset MSR[TS] if not recheckpointing" failed to apply to 4.14-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 6f5b9f018f4c7686fd944d920209d1382d320e4e Mon Sep 17 00:00:00 2001 From: Breno Leitao <leitao(a)debian.org> Date: Mon, 26 Nov 2018 18:12:00 -0200 Subject: [PATCH] powerpc/tm: Unset MSR[TS] if not recheckpointing MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit There is a TM Bad Thing bug that can be caused when you return from a signal context in a suspended transaction but with ucontext MSR[TS] unset. This forces regs->msr[TS] to be set at syscall entrance (since the CPU state is transactional). It also calls treclaim() to flush the transaction state, which is done based on the live (mfmsr) MSR state. Since user context MSR[TS] is not set, then restore_tm_sigcontexts() is not called, thus, not executing recheckpoint, keeping the CPU state as not transactional. When calling rfid, SRR1 will have MSR[TS] set, but the CPU state is non transactional, causing the TM Bad Thing with the following stack: [ 33.862316] Bad kernel stack pointer 3fffd9dce3e0 at c00000000000c47c cpu 0x8: Vector: 700 (Program Check) at [c00000003ff7fd40] pc: c00000000000c47c: fast_exception_return+0xac/0xb4 lr: 00003fff865f442c sp: 3fffd9dce3e0 msr: 8000000102a03031 current = 0xc00000041f68b700 paca = 0xc00000000fb84800 softe: 0 irq_happened: 0x01 pid = 1721, comm = tm-signal-sigre Linux version 4.9.0-3-powerpc64le (debian-kernel(a)lists.debian.org) (gcc version 6.3.0 20170516 (Debian 6.3.0-18) ) #1 SMP Debian 4.9.30-2+deb9u2 (2017-06-26) WARNING: exception is not recoverable, can't continue The same problem happens on 32-bits signal handler, and the fix is very similar, if tm_recheckpoint() is not executed, then regs->msr[TS] should be zeroed. This patch also fixes a sparse warning related to lack of indentation when CONFIG_PPC_TRANSACTIONAL_MEM is set. Fixes: 2b0a576d15e0e ("powerpc: Add new transactional memory state to the signal context") CC: Stable <stable(a)vger.kernel.org> # 3.10+ Signed-off-by: Breno Leitao <leitao(a)debian.org> Tested-by: Michal Suchánek <msuchanek(a)suse.de> Signed-off-by: Michael Ellerman <mpe(a)ellerman.id.au> diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c index 7484f43493d3..2d47cc79e5b3 100644 --- a/arch/powerpc/kernel/signal_32.c +++ b/arch/powerpc/kernel/signal_32.c @@ -1158,11 +1158,11 @@ SYSCALL_DEFINE0(rt_sigreturn) { struct rt_sigframe __user *rt_sf; struct pt_regs *regs = current_pt_regs(); + int tm_restore = 0; #ifdef CONFIG_PPC_TRANSACTIONAL_MEM struct ucontext __user *uc_transact; unsigned long msr_hi; unsigned long tmp; - int tm_restore = 0; #endif /* Always make any pending restarted system calls return -EINTR */ current->restart_block.fn = do_no_restart_syscall; @@ -1210,11 +1210,19 @@ SYSCALL_DEFINE0(rt_sigreturn) goto bad; } } - if (!tm_restore) - /* Fall through, for non-TM restore */ + if (!tm_restore) { + /* + * Unset regs->msr because ucontext MSR TS is not + * set, and recheckpoint was not called. This avoid + * hitting a TM Bad thing at RFID + */ + regs->msr &= ~MSR_TS_MASK; + } + /* Fall through, for non-TM restore */ #endif - if (do_setcontext(&rt_sf->uc, regs, 1)) - goto bad; + if (!tm_restore) + if (do_setcontext(&rt_sf->uc, regs, 1)) + goto bad; /* * It's not clear whether or why it is desirable to save the diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c index ba093ec5a21f..0935fe6c282a 100644 --- a/arch/powerpc/kernel/signal_64.c +++ b/arch/powerpc/kernel/signal_64.c @@ -757,11 +757,23 @@ SYSCALL_DEFINE0(rt_sigreturn) &uc_transact->uc_mcontext)) goto badframe; } - else - /* Fall through, for non-TM restore */ #endif - if (restore_sigcontext(current, NULL, 1, &uc->uc_mcontext)) - goto badframe; + /* Fall through, for non-TM restore */ + if (!MSR_TM_ACTIVE(msr)) { + /* + * Unset MSR[TS] on the thread regs since MSR from user + * context does not have MSR active, and recheckpoint was + * not called since restore_tm_sigcontexts() was not called + * also. + * + * If not unsetting it, the code can RFID to userspace with + * MSR[TS] set, but without CPU in the proper state, + * causing a TM bad thing. + */ + current->thread.regs->msr &= ~MSR_TS_MASK; + if (restore_sigcontext(current, NULL, 1, &uc->uc_mcontext)) + goto badframe; + } if (restore_altstack(&uc->uc_stack)) goto badframe;

5 years, 11 months

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FAILED: patch "[PATCH] powerpc/tm: Set MSR[TS] just prior to recheckpoint" failed to apply to 4.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From e1c3743e1a20647c53b719dbf28b48f45d23f2cd Mon Sep 17 00:00:00 2001 From: Breno Leitao <leitao(a)debian.org> Date: Wed, 21 Nov 2018 17:21:09 -0200 Subject: [PATCH] powerpc/tm: Set MSR[TS] just prior to recheckpoint On a signal handler return, the user could set a context with MSR[TS] bits set, and these bits would be copied to task regs->msr. At restore_tm_sigcontexts(), after current task regs->msr[TS] bits are set, several __get_user() are called and then a recheckpoint is executed. This is a problem since a page fault (in kernel space) could happen when calling __get_user(). If it happens, the process MSR[TS] bits were already set, but recheckpoint was not executed, and SPRs are still invalid. The page fault can cause the current process to be de-scheduled, with MSR[TS] active and without tm_recheckpoint() being called. More importantly, without TEXASR[FS] bit set also. Since TEXASR might not have the FS bit set, and when the process is scheduled back, it will try to reclaim, which will be aborted because of the CPU is not in the suspended state, and, then, recheckpoint. This recheckpoint will restore thread->texasr into TEXASR SPR, which might be zero, hitting a BUG_ON(). kernel BUG at /build/linux-sf3Co9/linux-4.9.30/arch/powerpc/kernel/tm.S:434! cpu 0xb: Vector: 700 (Program Check) at [c00000041f1576d0] pc: c000000000054550: restore_gprs+0xb0/0x180 lr: 0000000000000000 sp: c00000041f157950 msr: 8000000100021033 current = 0xc00000041f143000 paca = 0xc00000000fb86300 softe: 0 irq_happened: 0x01 pid = 1021, comm = kworker/11:1 kernel BUG at /build/linux-sf3Co9/linux-4.9.30/arch/powerpc/kernel/tm.S:434! Linux version 4.9.0-3-powerpc64le (debian-kernel(a)lists.debian.org) (gcc version 6.3.0 20170516 (Debian 6.3.0-18) ) #1 SMP Debian 4.9.30-2+deb9u2 (2017-06-26) enter ? for help [c00000041f157b30] c00000000001bc3c tm_recheckpoint.part.11+0x6c/0xa0 [c00000041f157b70] c00000000001d184 __switch_to+0x1e4/0x4c0 [c00000041f157bd0] c00000000082eeb8 __schedule+0x2f8/0x990 [c00000041f157cb0] c00000000082f598 schedule+0x48/0xc0 [c00000041f157ce0] c0000000000f0d28 worker_thread+0x148/0x610 [c00000041f157d80] c0000000000f96b0 kthread+0x120/0x140 [c00000041f157e30] c00000000000c0e0 ret_from_kernel_thread+0x5c/0x7c This patch simply delays the MSR[TS] set, so, if there is any page fault in the __get_user() section, it does not have regs->msr[TS] set, since the TM structures are still invalid, thus avoiding doing TM operations for in-kernel exceptions and possible process reschedule. With this patch, the MSR[TS] will only be set just before recheckpointing and setting TEXASR[FS] = 1, thus avoiding an interrupt with TM registers in invalid state. Other than that, if CONFIG_PREEMPT is set, there might be a preemption just after setting MSR[TS] and before tm_recheckpoint(), thus, this block must be atomic from a preemption perspective, thus, calling preempt_disable/enable() on this code. It is not possible to move tm_recheckpoint to happen earlier, because it is required to get the checkpointed registers from userspace, with __get_user(), thus, the only way to avoid this undesired behavior is delaying the MSR[TS] set. The 32-bits signal handler seems to be safe this current issue, but, it might be exposed to the preemption issue, thus, disabling preemption in this chunk of code. Changes from v2: * Run the critical section with preempt_disable. Fixes: 87b4e5393af7 ("powerpc/tm: Fix return of active 64bit signals") Cc: stable(a)vger.kernel.org (v3.9+) Signed-off-by: Breno Leitao <leitao(a)debian.org> Signed-off-by: Michael Ellerman <mpe(a)ellerman.id.au> diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c index 9d39e0eb03ff..7484f43493d3 100644 --- a/arch/powerpc/kernel/signal_32.c +++ b/arch/powerpc/kernel/signal_32.c @@ -848,7 +848,23 @@ static long restore_tm_user_regs(struct pt_regs *regs, /* If TM bits are set to the reserved value, it's an invalid context */ if (MSR_TM_RESV(msr_hi)) return 1; - /* Pull in the MSR TM bits from the user context */ + + /* + * Disabling preemption, since it is unsafe to be preempted + * with MSR[TS] set without recheckpointing. + */ + preempt_disable(); + + /* + * CAUTION: + * After regs->MSR[TS] being updated, make sure that get_user(), + * put_user() or similar functions are *not* called. These + * functions can generate page faults which will cause the process + * to be de-scheduled with MSR[TS] set but without calling + * tm_recheckpoint(). This can cause a bug. + * + * Pull in the MSR TM bits from the user context + */ regs->msr = (regs->msr & ~MSR_TS_MASK) | (msr_hi & MSR_TS_MASK); /* Now, recheckpoint. This loads up all of the checkpointed (older) * registers, including FP and V[S]Rs. After recheckpointing, the @@ -873,6 +889,8 @@ static long restore_tm_user_regs(struct pt_regs *regs, } #endif + preempt_enable(); + return 0; } #endif diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c index e53ad11be385..ba093ec5a21f 100644 --- a/arch/powerpc/kernel/signal_64.c +++ b/arch/powerpc/kernel/signal_64.c @@ -467,20 +467,6 @@ static long restore_tm_sigcontexts(struct task_struct *tsk, if (MSR_TM_RESV(msr)) return -EINVAL; - /* pull in MSR TS bits from user context */ - regs->msr = (regs->msr & ~MSR_TS_MASK) | (msr & MSR_TS_MASK); - - /* - * Ensure that TM is enabled in regs->msr before we leave the signal - * handler. It could be the case that (a) user disabled the TM bit - * through the manipulation of the MSR bits in uc_mcontext or (b) the - * TM bit was disabled because a sufficient number of context switches - * happened whilst in the signal handler and load_tm overflowed, - * disabling the TM bit. In either case we can end up with an illegal - * TM state leading to a TM Bad Thing when we return to userspace. - */ - regs->msr |= MSR_TM; - /* pull in MSR LE from user context */ regs->msr = (regs->msr & ~MSR_LE) | (msr & MSR_LE); @@ -572,6 +558,34 @@ static long restore_tm_sigcontexts(struct task_struct *tsk, tm_enable(); /* Make sure the transaction is marked as failed */ tsk->thread.tm_texasr |= TEXASR_FS; + + /* + * Disabling preemption, since it is unsafe to be preempted + * with MSR[TS] set without recheckpointing. + */ + preempt_disable(); + + /* pull in MSR TS bits from user context */ + regs->msr = (regs->msr & ~MSR_TS_MASK) | (msr & MSR_TS_MASK); + + /* + * Ensure that TM is enabled in regs->msr before we leave the signal + * handler. It could be the case that (a) user disabled the TM bit + * through the manipulation of the MSR bits in uc_mcontext or (b) the + * TM bit was disabled because a sufficient number of context switches + * happened whilst in the signal handler and load_tm overflowed, + * disabling the TM bit. In either case we can end up with an illegal + * TM state leading to a TM Bad Thing when we return to userspace. + * + * CAUTION: + * After regs->MSR[TS] being updated, make sure that get_user(), + * put_user() or similar functions are *not* called. These + * functions can generate page faults which will cause the process + * to be de-scheduled with MSR[TS] set but without calling + * tm_recheckpoint(). This can cause a bug. + */ + regs->msr |= MSR_TM; + /* This loads the checkpointed FP/VEC state, if used */ tm_recheckpoint(&tsk->thread); @@ -585,6 +599,8 @@ static long restore_tm_sigcontexts(struct task_struct *tsk, regs->msr |= MSR_VEC; } + preempt_enable(); + return err; } #endif

5 years, 11 months

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FAILED: patch "[PATCH] Btrfs: send, fix race with transaction commits that create" failed to apply to 4.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From be6821f82c3cc36e026f5afd10249988852b35ea Mon Sep 17 00:00:00 2001 From: Filipe Manana <fdmanana(a)suse.com> Date: Tue, 11 Dec 2018 10:19:45 +0000 Subject: [PATCH] Btrfs: send, fix race with transaction commits that create snapshots If we create a snapshot of a snapshot currently being used by a send operation, we can end up with send failing unexpectedly (returning -ENOENT error to user space for example). The following diagram shows how this happens. CPU 1 CPU2 CPU3 btrfs_ioctl_send() (...) create_snapshot() -> creates snapshot of a root used by the send task btrfs_commit_transaction() create_pending_snapshot() __get_inode_info() btrfs_search_slot() btrfs_search_slot_get_root() down_read commit_root_sem get reference on eb of the commit root -> eb with bytenr == X up_read commit_root_sem btrfs_cow_block(root node) btrfs_free_tree_block() -> creates delayed ref to free the extent btrfs_run_delayed_refs() -> runs the delayed ref, adds extent to fs_info->pinned_extents btrfs_finish_extent_commit() unpin_extent_range() -> marks extent as free in the free space cache transaction commit finishes btrfs_start_transaction() (...) btrfs_cow_block() btrfs_alloc_tree_block() btrfs_reserve_extent() -> allocates extent at bytenr == X btrfs_init_new_buffer(bytenr X) btrfs_find_create_tree_block() alloc_extent_buffer(bytenr X) find_extent_buffer(bytenr X) -> returns existing eb, which the send task got (...) -> modifies content of the eb with bytenr == X -> uses an eb that now belongs to some other tree and no more matches the commit root of the snapshot, resuts will be unpredictable The consequences of this race can be various, and can lead to searches in the commit root performed by the send task failing unexpectedly (unable to find inode items, returning -ENOENT to user space, for example) or not failing because an inode item with the same number was added to the tree that reused the metadata extent, in which case send can behave incorrectly in the worst case or just fail later for some reason. Fix this by performing a copy of the commit root's extent buffer when doing a search in the context of a send operation. CC: stable(a)vger.kernel.org # 4.4.x: 1fc28d8e2e9: Btrfs: move get root out of btrfs_search_slot to a helper CC: stable(a)vger.kernel.org # 4.4.x: f9ddfd0592a: Btrfs: remove unused check of skip_locking CC: stable(a)vger.kernel.org # 4.4.x Signed-off-by: Filipe Manana <fdmanana(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 72745235896f..4252e89df6ae 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -2587,14 +2587,27 @@ static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root, root_lock = BTRFS_READ_LOCK; if (p->search_commit_root) { - /* The commit roots are read only so we always do read locks */ - if (p->need_commit_sem) + /* + * The commit roots are read only so we always do read locks, + * and we always must hold the commit_root_sem when doing + * searches on them, the only exception is send where we don't + * want to block transaction commits for a long time, so + * we need to clone the commit root in order to avoid races + * with transaction commits that create a snapshot of one of + * the roots used by a send operation. + */ + if (p->need_commit_sem) { down_read(&fs_info->commit_root_sem); - b = root->commit_root; - extent_buffer_get(b); - level = btrfs_header_level(b); - if (p->need_commit_sem) + b = btrfs_clone_extent_buffer(root->commit_root); up_read(&fs_info->commit_root_sem); + if (!b) + return ERR_PTR(-ENOMEM); + + } else { + b = root->commit_root; + extent_buffer_get(b); + } + level = btrfs_header_level(b); /* * Ensure that all callers have set skip_locking when * p->search_commit_root = 1. @@ -2720,6 +2733,10 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root, again: prev_cmp = -1; b = btrfs_search_slot_get_root(root, p, write_lock_level); + if (IS_ERR(b)) { + ret = PTR_ERR(b); + goto done; + } while (b) { level = btrfs_header_level(b);

5 years, 11 months

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FAILED: patch "[PATCH] Btrfs: send, fix race with transaction commits that create" failed to apply to 4.9-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From be6821f82c3cc36e026f5afd10249988852b35ea Mon Sep 17 00:00:00 2001 From: Filipe Manana <fdmanana(a)suse.com> Date: Tue, 11 Dec 2018 10:19:45 +0000 Subject: [PATCH] Btrfs: send, fix race with transaction commits that create snapshots If we create a snapshot of a snapshot currently being used by a send operation, we can end up with send failing unexpectedly (returning -ENOENT error to user space for example). The following diagram shows how this happens. CPU 1 CPU2 CPU3 btrfs_ioctl_send() (...) create_snapshot() -> creates snapshot of a root used by the send task btrfs_commit_transaction() create_pending_snapshot() __get_inode_info() btrfs_search_slot() btrfs_search_slot_get_root() down_read commit_root_sem get reference on eb of the commit root -> eb with bytenr == X up_read commit_root_sem btrfs_cow_block(root node) btrfs_free_tree_block() -> creates delayed ref to free the extent btrfs_run_delayed_refs() -> runs the delayed ref, adds extent to fs_info->pinned_extents btrfs_finish_extent_commit() unpin_extent_range() -> marks extent as free in the free space cache transaction commit finishes btrfs_start_transaction() (...) btrfs_cow_block() btrfs_alloc_tree_block() btrfs_reserve_extent() -> allocates extent at bytenr == X btrfs_init_new_buffer(bytenr X) btrfs_find_create_tree_block() alloc_extent_buffer(bytenr X) find_extent_buffer(bytenr X) -> returns existing eb, which the send task got (...) -> modifies content of the eb with bytenr == X -> uses an eb that now belongs to some other tree and no more matches the commit root of the snapshot, resuts will be unpredictable The consequences of this race can be various, and can lead to searches in the commit root performed by the send task failing unexpectedly (unable to find inode items, returning -ENOENT to user space, for example) or not failing because an inode item with the same number was added to the tree that reused the metadata extent, in which case send can behave incorrectly in the worst case or just fail later for some reason. Fix this by performing a copy of the commit root's extent buffer when doing a search in the context of a send operation. CC: stable(a)vger.kernel.org # 4.4.x: 1fc28d8e2e9: Btrfs: move get root out of btrfs_search_slot to a helper CC: stable(a)vger.kernel.org # 4.4.x: f9ddfd0592a: Btrfs: remove unused check of skip_locking CC: stable(a)vger.kernel.org # 4.4.x Signed-off-by: Filipe Manana <fdmanana(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 72745235896f..4252e89df6ae 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -2587,14 +2587,27 @@ static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root, root_lock = BTRFS_READ_LOCK; if (p->search_commit_root) { - /* The commit roots are read only so we always do read locks */ - if (p->need_commit_sem) + /* + * The commit roots are read only so we always do read locks, + * and we always must hold the commit_root_sem when doing + * searches on them, the only exception is send where we don't + * want to block transaction commits for a long time, so + * we need to clone the commit root in order to avoid races + * with transaction commits that create a snapshot of one of + * the roots used by a send operation. + */ + if (p->need_commit_sem) { down_read(&fs_info->commit_root_sem); - b = root->commit_root; - extent_buffer_get(b); - level = btrfs_header_level(b); - if (p->need_commit_sem) + b = btrfs_clone_extent_buffer(root->commit_root); up_read(&fs_info->commit_root_sem); + if (!b) + return ERR_PTR(-ENOMEM); + + } else { + b = root->commit_root; + extent_buffer_get(b); + } + level = btrfs_header_level(b); /* * Ensure that all callers have set skip_locking when * p->search_commit_root = 1. @@ -2720,6 +2733,10 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root, again: prev_cmp = -1; b = btrfs_search_slot_get_root(root, p, write_lock_level); + if (IS_ERR(b)) { + ret = PTR_ERR(b); + goto done; + } while (b) { level = btrfs_header_level(b);

5 years, 11 months

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FAILED: patch "[PATCH] Btrfs: send, fix race with transaction commits that create" failed to apply to 4.14-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From be6821f82c3cc36e026f5afd10249988852b35ea Mon Sep 17 00:00:00 2001 From: Filipe Manana <fdmanana(a)suse.com> Date: Tue, 11 Dec 2018 10:19:45 +0000 Subject: [PATCH] Btrfs: send, fix race with transaction commits that create snapshots If we create a snapshot of a snapshot currently being used by a send operation, we can end up with send failing unexpectedly (returning -ENOENT error to user space for example). The following diagram shows how this happens. CPU 1 CPU2 CPU3 btrfs_ioctl_send() (...) create_snapshot() -> creates snapshot of a root used by the send task btrfs_commit_transaction() create_pending_snapshot() __get_inode_info() btrfs_search_slot() btrfs_search_slot_get_root() down_read commit_root_sem get reference on eb of the commit root -> eb with bytenr == X up_read commit_root_sem btrfs_cow_block(root node) btrfs_free_tree_block() -> creates delayed ref to free the extent btrfs_run_delayed_refs() -> runs the delayed ref, adds extent to fs_info->pinned_extents btrfs_finish_extent_commit() unpin_extent_range() -> marks extent as free in the free space cache transaction commit finishes btrfs_start_transaction() (...) btrfs_cow_block() btrfs_alloc_tree_block() btrfs_reserve_extent() -> allocates extent at bytenr == X btrfs_init_new_buffer(bytenr X) btrfs_find_create_tree_block() alloc_extent_buffer(bytenr X) find_extent_buffer(bytenr X) -> returns existing eb, which the send task got (...) -> modifies content of the eb with bytenr == X -> uses an eb that now belongs to some other tree and no more matches the commit root of the snapshot, resuts will be unpredictable The consequences of this race can be various, and can lead to searches in the commit root performed by the send task failing unexpectedly (unable to find inode items, returning -ENOENT to user space, for example) or not failing because an inode item with the same number was added to the tree that reused the metadata extent, in which case send can behave incorrectly in the worst case or just fail later for some reason. Fix this by performing a copy of the commit root's extent buffer when doing a search in the context of a send operation. CC: stable(a)vger.kernel.org # 4.4.x: 1fc28d8e2e9: Btrfs: move get root out of btrfs_search_slot to a helper CC: stable(a)vger.kernel.org # 4.4.x: f9ddfd0592a: Btrfs: remove unused check of skip_locking CC: stable(a)vger.kernel.org # 4.4.x Signed-off-by: Filipe Manana <fdmanana(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 72745235896f..4252e89df6ae 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -2587,14 +2587,27 @@ static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root, root_lock = BTRFS_READ_LOCK; if (p->search_commit_root) { - /* The commit roots are read only so we always do read locks */ - if (p->need_commit_sem) + /* + * The commit roots are read only so we always do read locks, + * and we always must hold the commit_root_sem when doing + * searches on them, the only exception is send where we don't + * want to block transaction commits for a long time, so + * we need to clone the commit root in order to avoid races + * with transaction commits that create a snapshot of one of + * the roots used by a send operation. + */ + if (p->need_commit_sem) { down_read(&fs_info->commit_root_sem); - b = root->commit_root; - extent_buffer_get(b); - level = btrfs_header_level(b); - if (p->need_commit_sem) + b = btrfs_clone_extent_buffer(root->commit_root); up_read(&fs_info->commit_root_sem); + if (!b) + return ERR_PTR(-ENOMEM); + + } else { + b = root->commit_root; + extent_buffer_get(b); + } + level = btrfs_header_level(b); /* * Ensure that all callers have set skip_locking when * p->search_commit_root = 1. @@ -2720,6 +2733,10 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root, again: prev_cmp = -1; b = btrfs_search_slot_get_root(root, p, write_lock_level); + if (IS_ERR(b)) { + ret = PTR_ERR(b); + goto done; + } while (b) { level = btrfs_header_level(b);

5 years, 11 months

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FAILED: patch "[PATCH] btrfs: Fix error handling in btrfs_cleanup_ordered_extents" failed to apply to 4.14-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From d1051d6ebf8ef3517a5a3cf82bba8436d190f1c2 Mon Sep 17 00:00:00 2001 From: Nikolay Borisov <nborisov(a)suse.com> Date: Wed, 21 Nov 2018 17:10:52 +0200 Subject: [PATCH] btrfs: Fix error handling in btrfs_cleanup_ordered_extents Running btrfs/124 in a loop hung up on me sporadically with the following call trace: btrfs D 0 5760 5324 0x00000000 Call Trace: ? __schedule+0x243/0x800 schedule+0x33/0x90 btrfs_start_ordered_extent+0x10c/0x1b0 [btrfs] ? wait_woken+0xa0/0xa0 btrfs_wait_ordered_range+0xbb/0x100 [btrfs] btrfs_relocate_block_group+0x1ff/0x230 [btrfs] btrfs_relocate_chunk+0x49/0x100 [btrfs] btrfs_balance+0xbeb/0x1740 [btrfs] btrfs_ioctl_balance+0x2ee/0x380 [btrfs] btrfs_ioctl+0x1691/0x3110 [btrfs] ? lockdep_hardirqs_on+0xed/0x180 ? __handle_mm_fault+0x8e7/0xfb0 ? _raw_spin_unlock+0x24/0x30 ? __handle_mm_fault+0x8e7/0xfb0 ? do_vfs_ioctl+0xa5/0x6e0 ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs] do_vfs_ioctl+0xa5/0x6e0 ? entry_SYSCALL_64_after_hwframe+0x3e/0xbe ksys_ioctl+0x3a/0x70 __x64_sys_ioctl+0x16/0x20 do_syscall_64+0x60/0x1b0 entry_SYSCALL_64_after_hwframe+0x49/0xbe This happens because during page writeback it's valid for writepage_delalloc to instantiate a delalloc range which doesn't belong to the page currently being written back. The reason this case is valid is due to find_lock_delalloc_range returning any available range after the passed delalloc_start and ignoring whether the page under writeback is within that range. In turn ordered extents (OE) are always created for the returned range from find_lock_delalloc_range. If, however, a failure occurs while OE are being created then the clean up code in btrfs_cleanup_ordered_extents will be called. Unfortunately the code in btrfs_cleanup_ordered_extents doesn't consider the case of such 'foreign' range being processed and instead it always assumes that the range OE are created for belongs to the page. This leads to the first page of such foregin range to not be cleaned up since it's deliberately missed and skipped by the current cleaning up code. Fix this by correctly checking whether the current page belongs to the range being instantiated and if so adjsut the range parameters passed for cleaning up. If it doesn't, then just clean the whole OE range directly. Fixes: 524272607e88 ("btrfs: Handle delalloc error correctly to avoid ordered extent hang") CC: stable(a)vger.kernel.org # 4.14+ Reviewed-by: Josef Bacik <josef(a)toxicpanda.com> Signed-off-by: Nikolay Borisov <nborisov(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index e7b97c699acf..e1451a69432b 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -110,17 +110,17 @@ static void __endio_write_update_ordered(struct inode *inode, * extent_clear_unlock_delalloc() to clear both the bits EXTENT_DO_ACCOUNTING * and EXTENT_DELALLOC simultaneously, because that causes the reserved metadata * to be released, which we want to happen only when finishing the ordered - * extent (btrfs_finish_ordered_io()). Also note that the caller of - * btrfs_run_delalloc_range already does proper cleanup for the first page of - * the range, that is, it invokes the callback writepage_end_io_hook() for the - * range of the first page. + * extent (btrfs_finish_ordered_io()). */ static inline void btrfs_cleanup_ordered_extents(struct inode *inode, - const u64 offset, - const u64 bytes) + struct page *locked_page, + u64 offset, u64 bytes) { unsigned long index = offset >> PAGE_SHIFT; unsigned long end_index = (offset + bytes - 1) >> PAGE_SHIFT; + u64 page_start = page_offset(locked_page); + u64 page_end = page_start + PAGE_SIZE - 1; + struct page *page; while (index <= end_index) { @@ -131,8 +131,18 @@ static inline void btrfs_cleanup_ordered_extents(struct inode *inode, ClearPagePrivate2(page); put_page(page); } - return __endio_write_update_ordered(inode, offset + PAGE_SIZE, - bytes - PAGE_SIZE, false); + + /* + * In case this page belongs to the delalloc range being instantiated + * then skip it, since the first page of a range is going to be + * properly cleaned up by the caller of run_delalloc_range + */ + if (page_start >= offset && page_end <= (offset + bytes - 1)) { + offset += PAGE_SIZE; + bytes -= PAGE_SIZE; + } + + return __endio_write_update_ordered(inode, offset, bytes, false); } static int btrfs_dirty_inode(struct inode *inode); @@ -1603,7 +1613,8 @@ int btrfs_run_delalloc_range(void *private_data, struct page *locked_page, write_flags); } if (ret) - btrfs_cleanup_ordered_extents(inode, start, end - start + 1); + btrfs_cleanup_ordered_extents(inode, locked_page, start, + end - start + 1); return ret; }

5 years, 11 months

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FAILED: patch "[PATCH] btrfs: Fix error handling in btrfs_cleanup_ordered_extents" failed to apply to 4.19-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From d1051d6ebf8ef3517a5a3cf82bba8436d190f1c2 Mon Sep 17 00:00:00 2001 From: Nikolay Borisov <nborisov(a)suse.com> Date: Wed, 21 Nov 2018 17:10:52 +0200 Subject: [PATCH] btrfs: Fix error handling in btrfs_cleanup_ordered_extents Running btrfs/124 in a loop hung up on me sporadically with the following call trace: btrfs D 0 5760 5324 0x00000000 Call Trace: ? __schedule+0x243/0x800 schedule+0x33/0x90 btrfs_start_ordered_extent+0x10c/0x1b0 [btrfs] ? wait_woken+0xa0/0xa0 btrfs_wait_ordered_range+0xbb/0x100 [btrfs] btrfs_relocate_block_group+0x1ff/0x230 [btrfs] btrfs_relocate_chunk+0x49/0x100 [btrfs] btrfs_balance+0xbeb/0x1740 [btrfs] btrfs_ioctl_balance+0x2ee/0x380 [btrfs] btrfs_ioctl+0x1691/0x3110 [btrfs] ? lockdep_hardirqs_on+0xed/0x180 ? __handle_mm_fault+0x8e7/0xfb0 ? _raw_spin_unlock+0x24/0x30 ? __handle_mm_fault+0x8e7/0xfb0 ? do_vfs_ioctl+0xa5/0x6e0 ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs] do_vfs_ioctl+0xa5/0x6e0 ? entry_SYSCALL_64_after_hwframe+0x3e/0xbe ksys_ioctl+0x3a/0x70 __x64_sys_ioctl+0x16/0x20 do_syscall_64+0x60/0x1b0 entry_SYSCALL_64_after_hwframe+0x49/0xbe This happens because during page writeback it's valid for writepage_delalloc to instantiate a delalloc range which doesn't belong to the page currently being written back. The reason this case is valid is due to find_lock_delalloc_range returning any available range after the passed delalloc_start and ignoring whether the page under writeback is within that range. In turn ordered extents (OE) are always created for the returned range from find_lock_delalloc_range. If, however, a failure occurs while OE are being created then the clean up code in btrfs_cleanup_ordered_extents will be called. Unfortunately the code in btrfs_cleanup_ordered_extents doesn't consider the case of such 'foreign' range being processed and instead it always assumes that the range OE are created for belongs to the page. This leads to the first page of such foregin range to not be cleaned up since it's deliberately missed and skipped by the current cleaning up code. Fix this by correctly checking whether the current page belongs to the range being instantiated and if so adjsut the range parameters passed for cleaning up. If it doesn't, then just clean the whole OE range directly. Fixes: 524272607e88 ("btrfs: Handle delalloc error correctly to avoid ordered extent hang") CC: stable(a)vger.kernel.org # 4.14+ Reviewed-by: Josef Bacik <josef(a)toxicpanda.com> Signed-off-by: Nikolay Borisov <nborisov(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index e7b97c699acf..e1451a69432b 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -110,17 +110,17 @@ static void __endio_write_update_ordered(struct inode *inode, * extent_clear_unlock_delalloc() to clear both the bits EXTENT_DO_ACCOUNTING * and EXTENT_DELALLOC simultaneously, because that causes the reserved metadata * to be released, which we want to happen only when finishing the ordered - * extent (btrfs_finish_ordered_io()). Also note that the caller of - * btrfs_run_delalloc_range already does proper cleanup for the first page of - * the range, that is, it invokes the callback writepage_end_io_hook() for the - * range of the first page. + * extent (btrfs_finish_ordered_io()). */ static inline void btrfs_cleanup_ordered_extents(struct inode *inode, - const u64 offset, - const u64 bytes) + struct page *locked_page, + u64 offset, u64 bytes) { unsigned long index = offset >> PAGE_SHIFT; unsigned long end_index = (offset + bytes - 1) >> PAGE_SHIFT; + u64 page_start = page_offset(locked_page); + u64 page_end = page_start + PAGE_SIZE - 1; + struct page *page; while (index <= end_index) { @@ -131,8 +131,18 @@ static inline void btrfs_cleanup_ordered_extents(struct inode *inode, ClearPagePrivate2(page); put_page(page); } - return __endio_write_update_ordered(inode, offset + PAGE_SIZE, - bytes - PAGE_SIZE, false); + + /* + * In case this page belongs to the delalloc range being instantiated + * then skip it, since the first page of a range is going to be + * properly cleaned up by the caller of run_delalloc_range + */ + if (page_start >= offset && page_end <= (offset + bytes - 1)) { + offset += PAGE_SIZE; + bytes -= PAGE_SIZE; + } + + return __endio_write_update_ordered(inode, offset, bytes, false); } static int btrfs_dirty_inode(struct inode *inode); @@ -1603,7 +1613,8 @@ int btrfs_run_delalloc_range(void *private_data, struct page *locked_page, write_flags); } if (ret) - btrfs_cleanup_ordered_extents(inode, start, end - start + 1); + btrfs_cleanup_ordered_extents(inode, locked_page, start, + end - start + 1); return ret; }

5 years, 11 months

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FAILED: patch "[PATCH] btrfs: Fix error handling in btrfs_cleanup_ordered_extents" failed to apply to 4.20-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.20-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From d1051d6ebf8ef3517a5a3cf82bba8436d190f1c2 Mon Sep 17 00:00:00 2001 From: Nikolay Borisov <nborisov(a)suse.com> Date: Wed, 21 Nov 2018 17:10:52 +0200 Subject: [PATCH] btrfs: Fix error handling in btrfs_cleanup_ordered_extents Running btrfs/124 in a loop hung up on me sporadically with the following call trace: btrfs D 0 5760 5324 0x00000000 Call Trace: ? __schedule+0x243/0x800 schedule+0x33/0x90 btrfs_start_ordered_extent+0x10c/0x1b0 [btrfs] ? wait_woken+0xa0/0xa0 btrfs_wait_ordered_range+0xbb/0x100 [btrfs] btrfs_relocate_block_group+0x1ff/0x230 [btrfs] btrfs_relocate_chunk+0x49/0x100 [btrfs] btrfs_balance+0xbeb/0x1740 [btrfs] btrfs_ioctl_balance+0x2ee/0x380 [btrfs] btrfs_ioctl+0x1691/0x3110 [btrfs] ? lockdep_hardirqs_on+0xed/0x180 ? __handle_mm_fault+0x8e7/0xfb0 ? _raw_spin_unlock+0x24/0x30 ? __handle_mm_fault+0x8e7/0xfb0 ? do_vfs_ioctl+0xa5/0x6e0 ? btrfs_ioctl_get_supported_features+0x30/0x30 [btrfs] do_vfs_ioctl+0xa5/0x6e0 ? entry_SYSCALL_64_after_hwframe+0x3e/0xbe ksys_ioctl+0x3a/0x70 __x64_sys_ioctl+0x16/0x20 do_syscall_64+0x60/0x1b0 entry_SYSCALL_64_after_hwframe+0x49/0xbe This happens because during page writeback it's valid for writepage_delalloc to instantiate a delalloc range which doesn't belong to the page currently being written back. The reason this case is valid is due to find_lock_delalloc_range returning any available range after the passed delalloc_start and ignoring whether the page under writeback is within that range. In turn ordered extents (OE) are always created for the returned range from find_lock_delalloc_range. If, however, a failure occurs while OE are being created then the clean up code in btrfs_cleanup_ordered_extents will be called. Unfortunately the code in btrfs_cleanup_ordered_extents doesn't consider the case of such 'foreign' range being processed and instead it always assumes that the range OE are created for belongs to the page. This leads to the first page of such foregin range to not be cleaned up since it's deliberately missed and skipped by the current cleaning up code. Fix this by correctly checking whether the current page belongs to the range being instantiated and if so adjsut the range parameters passed for cleaning up. If it doesn't, then just clean the whole OE range directly. Fixes: 524272607e88 ("btrfs: Handle delalloc error correctly to avoid ordered extent hang") CC: stable(a)vger.kernel.org # 4.14+ Reviewed-by: Josef Bacik <josef(a)toxicpanda.com> Signed-off-by: Nikolay Borisov <nborisov(a)suse.com> Signed-off-by: David Sterba <dsterba(a)suse.com> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index e7b97c699acf..e1451a69432b 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -110,17 +110,17 @@ static void __endio_write_update_ordered(struct inode *inode, * extent_clear_unlock_delalloc() to clear both the bits EXTENT_DO_ACCOUNTING * and EXTENT_DELALLOC simultaneously, because that causes the reserved metadata * to be released, which we want to happen only when finishing the ordered - * extent (btrfs_finish_ordered_io()). Also note that the caller of - * btrfs_run_delalloc_range already does proper cleanup for the first page of - * the range, that is, it invokes the callback writepage_end_io_hook() for the - * range of the first page. + * extent (btrfs_finish_ordered_io()). */ static inline void btrfs_cleanup_ordered_extents(struct inode *inode, - const u64 offset, - const u64 bytes) + struct page *locked_page, + u64 offset, u64 bytes) { unsigned long index = offset >> PAGE_SHIFT; unsigned long end_index = (offset + bytes - 1) >> PAGE_SHIFT; + u64 page_start = page_offset(locked_page); + u64 page_end = page_start + PAGE_SIZE - 1; + struct page *page; while (index <= end_index) { @@ -131,8 +131,18 @@ static inline void btrfs_cleanup_ordered_extents(struct inode *inode, ClearPagePrivate2(page); put_page(page); } - return __endio_write_update_ordered(inode, offset + PAGE_SIZE, - bytes - PAGE_SIZE, false); + + /* + * In case this page belongs to the delalloc range being instantiated + * then skip it, since the first page of a range is going to be + * properly cleaned up by the caller of run_delalloc_range + */ + if (page_start >= offset && page_end <= (offset + bytes - 1)) { + offset += PAGE_SIZE; + bytes -= PAGE_SIZE; + } + + return __endio_write_update_ordered(inode, offset, bytes, false); } static int btrfs_dirty_inode(struct inode *inode); @@ -1603,7 +1613,8 @@ int btrfs_run_delalloc_range(void *private_data, struct page *locked_page, write_flags); } if (ret) - btrfs_cleanup_ordered_extents(inode, start, end - start + 1); + btrfs_cleanup_ordered_extents(inode, locked_page, start, + end - start + 1); return ret; }

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Linux-stable-mirror January 2019