> The patch below does not apply to the 3.10-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 <[email protected]>.
>
In my check, this patch is cleanly applied on top of 3.10.45 + commit
74614de17db6 ("mm/memory-failure.c: don't let collect_procs() skip
over processes for MF_ACTION_REQUIRED").
There might have been a conflict with other patches newly backported
to stable. Could you show me how you failed to apply?
Thanks,
Naoya Horiguchi
> ------------------ original commit in Linus's tree ------------------
>
> From 3ba08129e38437561df44c36b7ea9081185d5333 Mon Sep 17 00:00:00 2001
> From: Naoya Horiguchi <[email protected]>
> Date: Wed, 4 Jun 2014 16:11:02 -0700
> Subject: [PATCH] mm/memory-failure.c: support use of a dedicated thread to
> handle SIGBUS(BUS_MCEERR_AO)
>
> Currently memory error handler handles action optional errors in the
> deferred manner by default. And if a recovery aware application wants
> to handle it immediately, it can do it by setting PF_MCE_EARLY flag.
> However, such signal can be sent only to the main thread, so it's
> problematic if the application wants to have a dedicated thread to
> handler such signals.
>
> So this patch adds dedicated thread support to memory error handler. We
> have PF_MCE_EARLY flags for each thread separately, so with this patch
> AO signal is sent to the thread with PF_MCE_EARLY flag set, not the main
> thread. If you want to implement a dedicated thread, you call prctl()
> to set PF_MCE_EARLY on the thread.
>
> Memory error handler collects processes to be killed, so this patch lets
> it check PF_MCE_EARLY flag on each thread in the collecting routines.
>
> No behavioral change for all non-early kill cases.
>
> Tony said:
>
> : The old behavior was crazy - someone with a multithreaded process might
> : well expect that if they call prctl(PF_MCE_EARLY) in just one thread, then
> : that thread would see the SIGBUS with si_code = BUS_MCEERR_A0 - even if
> : that thread wasn't the main thread for the process.
>
> [[email protected]: coding-style fixes]
> Signed-off-by: Naoya Horiguchi <[email protected]>
> Reviewed-by: Tony Luck <[email protected]>
> Cc: Kamil Iskra <[email protected]>
> Cc: Andi Kleen <[email protected]>
> Cc: Borislav Petkov <[email protected]>
> Cc: Chen Gong <[email protected]>
> Cc: <[email protected]> [3.2+]
> Signed-off-by: Andrew Morton <[email protected]>
> Signed-off-by: Linus Torvalds <[email protected]>
>
> diff --git a/Documentation/vm/hwpoison.txt b/Documentation/vm/hwpoison.txt
> index 550068466605..6ae89a9edf2a 100644
> --- a/Documentation/vm/hwpoison.txt
> +++ b/Documentation/vm/hwpoison.txt
> @@ -84,6 +84,11 @@ PR_MCE_KILL
> PR_MCE_KILL_EARLY: Early kill
> PR_MCE_KILL_LATE: Late kill
> PR_MCE_KILL_DEFAULT: Use system global default
> + Note that if you want to have a dedicated thread which handles
> + the SIGBUS(BUS_MCEERR_AO) on behalf of the process, you should
> + call prctl(PR_MCE_KILL_EARLY) on the designated thread. Otherwise,
> + the SIGBUS is sent to the main thread.
> +
> PR_MCE_KILL_GET
> return current mode
>
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index ed339c505d55..cd8989c1027e 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -380,15 +380,44 @@ static void kill_procs(struct list_head *to_kill, int
> forcekill, int trapno,
> }
> }
>
> -static int task_early_kill(struct task_struct *tsk, int force_early)
> +/*
> + * Find a dedicated thread which is supposed to handle SIGBUS(BUS_MCEERR_AO)
> + * on behalf of the thread group. Return task_struct of the (first found)
> + * dedicated thread if found, and return NULL otherwise.
> + *
> + * We already hold read_lock(&tasklist_lock) in the caller, so we don't
> + * have to call rcu_read_lock/unlock() in this function.
> + */
> +static struct task_struct *find_early_kill_thread(struct task_struct *tsk)
> +{
> + struct task_struct *t;
> +
> + for_each_thread(tsk, t)
> + if ((t->flags & PF_MCE_PROCESS) && (t->flags & PF_MCE_EARLY))
> + return t;
> + return NULL;
> +}
> +
> +/*
> + * Determine whether a given process is "early kill" process which expects
> + * to be signaled when some page under the process is hwpoisoned.
> + * Return task_struct of the dedicated thread (main thread unless explicitly
> + * specified) if the process is "early kill," and otherwise returns NULL.
> + */
> +static struct task_struct *task_early_kill(struct task_struct *tsk,
> + int force_early)
> {
> + struct task_struct *t;
> if (!tsk->mm)
> - return 0;
> + return NULL;
> if (force_early)
> - return 1;
> - if (tsk->flags & PF_MCE_PROCESS)
> - return !!(tsk->flags & PF_MCE_EARLY);
> - return sysctl_memory_failure_early_kill;
> + return tsk;
> + t = find_early_kill_thread(tsk);
> + if (t)
> + return t;
> + if (sysctl_memory_failure_early_kill)
> + return tsk;
> + return NULL;
> }
>
> /*
> @@ -410,16 +439,17 @@ static void collect_procs_anon(struct page *page,
> struct list_head *to_kill,
> read_lock(&tasklist_lock);
> for_each_process (tsk) {
> struct anon_vma_chain *vmac;
> + struct task_struct *t = task_early_kill(tsk, force_early);
>
> - if (!task_early_kill(tsk, force_early))
> + if (!t)
> continue;
> anon_vma_interval_tree_foreach(vmac, &av->rb_root,
> pgoff, pgoff) {
> vma = vmac->vma;
> if (!page_mapped_in_vma(page, vma))
> continue;
> - if (vma->vm_mm == tsk->mm)
> - add_to_kill(tsk, page, vma, to_kill, tkc);
> + if (vma->vm_mm == t->mm)
> + add_to_kill(t, page, vma, to_kill, tkc);
> }
> }
> read_unlock(&tasklist_lock);
> @@ -440,10 +470,10 @@ static void collect_procs_file(struct page *page,
> struct list_head *to_kill,
> read_lock(&tasklist_lock);
> for_each_process(tsk) {
> pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
> + struct task_struct *t = task_early_kill(tsk, force_early);
>
> - if (!task_early_kill(tsk, force_early))
> + if (!t)
> continue;
> -
> vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff,
> pgoff) {
> /*
> @@ -453,8 +483,8 @@ static void collect_procs_file(struct page *page, struct
> list_head *to_kill,
> * Assume applications who requested early kill want
> * to be informed of all such data corruptions.
> */
> - if (vma->vm_mm == tsk->mm)
> - add_to_kill(tsk, page, vma, to_kill, tkc);
> + if (vma->vm_mm == t->mm)
> + add_to_kill(t, page, vma, to_kill, tkc);
> }
> }
> read_unlock(&tasklist_lock);
On Mon, Jun 30, 2014 at 10:16:20AM -0500, Horiguchi, Naoya wrote:
> The patch below does not apply to the 3.10-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 <[email protected]>.
>
> thanks,
>
> greg k-h
>
> ------------------ original commit in Linus's tree ------------------
>
> From 3ba08129e38437561df44c36b7ea9081185d5333 Mon Sep 17 00:00:00 2001
> From: Naoya Horiguchi <[email protected]>
> Date: Wed, 4 Jun 2014 16:11:02 -0700
> Subject: [PATCH] mm/memory-failure.c: support use of a dedicated thread to
> handle SIGBUS(BUS_MCEERR_AO)
>
> Currently memory error handler handles action optional errors in the
> deferred manner by default. And if a recovery aware application wants
> to handle it immediately, it can do it by setting PF_MCE_EARLY flag.
> However, such signal can be sent only to the main thread, so it's
> problematic if the application wants to have a dedicated thread to
> handler such signals.
>
> So this patch adds dedicated thread support to memory error handler. We
> have PF_MCE_EARLY flags for each thread separately, so with this patch
> AO signal is sent to the thread with PF_MCE_EARLY flag set, not the main
> thread. If you want to implement a dedicated thread, you call prctl()
> to set PF_MCE_EARLY on the thread.
>
> Memory error handler collects processes to be killed, so this patch lets
> it check PF_MCE_EARLY flag on each thread in the collecting routines.
>
> No behavioral change for all non-early kill cases.
>
> Tony said:
>
> : The old behavior was crazy - someone with a multithreaded process might
> : well expect that if they call prctl(PF_MCE_EARLY) in just one thread, then
> : that thread would see the SIGBUS with si_code = BUS_MCEERR_A0 - even if
> : that thread wasn't the main thread for the process.
>
> [[email protected]: coding-style fixes]
> Signed-off-by: Naoya Horiguchi <[email protected]>
> Reviewed-by: Tony Luck <[email protected]>
> Cc: Kamil Iskra <[email protected]>
> Cc: Andi Kleen <[email protected]>
> Cc: Borislav Petkov <[email protected]>
> Cc: Chen Gong <[email protected]>
> Cc: <[email protected]> [3.2+]
> Signed-off-by: Andrew Morton <[email protected]>
> Signed-off-by: Linus Torvalds <[email protected]>
>
> diff --git a/Documentation/vm/hwpoison.txt b/Documentation/vm/hwpoison.txt
> index 550068466605..6ae89a9edf2a 100644
> --- a/Documentation/vm/hwpoison.txt
> +++ b/Documentation/vm/hwpoison.txt
> @@ -84,6 +84,11 @@ PR_MCE_KILL
> PR_MCE_KILL_EARLY: Early kill
> PR_MCE_KILL_LATE: Late kill
> PR_MCE_KILL_DEFAULT: Use system global default
> + Note that if you want to have a dedicated thread which handles
> + the SIGBUS(BUS_MCEERR_AO) on behalf of the process, you should
> + call prctl(PR_MCE_KILL_EARLY) on the designated thread. Otherwise,
> + the SIGBUS is sent to the main thread.
> +
> PR_MCE_KILL_GET
> return current mode
>
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index ed339c505d55..cd8989c1027e 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -380,15 +380,44 @@ static void kill_procs(struct list_head *to_kill, int
> forcekill, int trapno,
> }
> }
>
> -static int task_early_kill(struct task_struct *tsk, int force_early)
> +/*
> + * Find a dedicated thread which is supposed to handle SIGBUS(BUS_MCEERR_AO)
> + * on behalf of the thread group. Return task_struct of the (first found)
> + * dedicated thread if found, and return NULL otherwise.
> + *
> + * We already hold read_lock(&tasklist_lock) in the caller, so we don't
> + * have to call rcu_read_lock/unlock() in this function.
> + */
> +static struct task_struct *find_early_kill_thread(struct task_struct *tsk)
> +{
> + struct task_struct *t;
> +
> + for_each_thread(tsk, t)
> + if ((t->flags & PF_MCE_PROCESS) && (t->flags & PF_MCE_EARLY))
> + return t;
> + return NULL;
> +}
> +
> +/*
> + * Determine whether a given process is "early kill" process which expects
> + * to be signaled when some page under the process is hwpoisoned.
> + * Return task_struct of the dedicated thread (main thread unless explicitly
> + * specified) if the process is "early kill," and otherwise returns NULL.
> + */
> +static struct task_struct *task_early_kill(struct task_struct *tsk,
> + int force_early)
> {
> + struct task_struct *t;
> if (!tsk->mm)
> - return 0;
> + return NULL;
> if (force_early)
> - return 1;
> - if (tsk->flags & PF_MCE_PROCESS)
> - return !!(tsk->flags & PF_MCE_EARLY);
> - return sysctl_memory_failure_early_kill;
> + return tsk;
> + t = find_early_kill_thread(tsk);
> + if (t)
> + return t;
> + if (sysctl_memory_failure_early_kill)
> + return tsk;
> + return NULL;
> }
>
> /*
> @@ -410,16 +439,17 @@ static void collect_procs_anon(struct page *page,
> struct list_head *to_kill,
> read_lock(&tasklist_lock);
> for_each_process (tsk) {
> struct anon_vma_chain *vmac;
> + struct task_struct *t = task_early_kill(tsk, force_early);
>
> - if (!task_early_kill(tsk, force_early))
> + if (!t)
> continue;
> anon_vma_interval_tree_foreach(vmac, &av->rb_root,
> pgoff, pgoff) {
> vma = vmac->vma;
> if (!page_mapped_in_vma(page, vma))
> continue;
> - if (vma->vm_mm == tsk->mm)
> - add_to_kill(tsk, page, vma, to_kill, tkc);
> + if (vma->vm_mm == t->mm)
> + add_to_kill(t, page, vma, to_kill, tkc);
> }
> }
> read_unlock(&tasklist_lock);
> @@ -440,10 +470,10 @@ static void collect_procs_file(struct page *page,
> struct list_head *to_kill,
> read_lock(&tasklist_lock);
> for_each_process(tsk) {
> pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
> + struct task_struct *t = task_early_kill(tsk, force_early);
>
> - if (!task_early_kill(tsk, force_early))
> + if (!t)
> continue;
> -
> vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff,
> pgoff) {
> /*
> @@ -453,8 +483,8 @@ static void collect_procs_file(struct page *page, struct
> list_head *to_kill,
> * Assume applications who requested early kill want
> * to be informed of all such data corruptions.
> */
> - if (vma->vm_mm == tsk->mm)
> - add_to_kill(tsk, page, vma, to_kill, tkc);
> + if (vma->vm_mm == t->mm)
> + add_to_kill(t, page, vma, to_kill, tkc);
> }
> }
> read_unlock(&tasklist_lock);
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
