Re: [PATCH v7 3/8] mm: factor helpers for memory_failure_dev_pagemap
On Fri, Sep 24, 2021 at 09:09:54PM +0800, Shiyang Ruan wrote:
> memory_failure_dev_pagemap code is a bit complex before introduce RMAP
> feature for fsdax. So it is needed to factor some helper functions to
> simplify these code.
>
> Signed-off-by: Shiyang Ruan
> ---
> mm/memory-failure.c | 140
> 1 file changed, 76 insertions(+), 64 deletions(-)
>
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 54879c339024..8ff9b52823c0 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1430,6 +1430,79 @@ static int try_to_split_thp_page(struct page *page,
> const char *msg)
> return 0;
> }
>
> +static void unmap_and_kill(struct list_head *to_kill, unsigned long pfn,
> + struct address_space *mapping, pgoff_t index, int flags)
> +{
> + struct to_kill *tk;
> + unsigned long size = 0;
> +
> + list_for_each_entry(tk, to_kill, nd)
> + if (tk->size_shift)
> + size = max(size, 1UL << tk->size_shift);
> + if (size) {
Nit: an empty line here would be nice for readability.
> + if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
> + /*
> + * TODO: Handle HMM pages which may need coordination
> + * with device-side memory.
> + */
> + return -EBUSY;
We've got rid of the HMM terminology for device private memory, so
I'd reword this update the comment to follow that while you're at it.
Otherwise looks good:
Reviewed-by: Christoph Hellwig
Re: [PATCH v7 3/8] mm: factor helpers for memory_failure_dev_pagemap
On Fri, Sep 24, 2021 at 09:09:54PM +0800, Shiyang Ruan wrote:
> memory_failure_dev_pagemap code is a bit complex before introduce RMAP
> feature for fsdax. So it is needed to factor some helper functions to
> simplify these code.
>
> Signed-off-by: Shiyang Ruan
This looks like a reasonable hoist...
Reviewed-by: Darrick J. Wong
--D
> ---
> mm/memory-failure.c | 140
> 1 file changed, 76 insertions(+), 64 deletions(-)
>
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 54879c339024..8ff9b52823c0 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1430,6 +1430,79 @@ static int try_to_split_thp_page(struct page *page,
> const char *msg)
> return 0;
> }
>
> +static void unmap_and_kill(struct list_head *to_kill, unsigned long pfn,
> + struct address_space *mapping, pgoff_t index, int flags)
> +{
> + struct to_kill *tk;
> + unsigned long size = 0;
> +
> + list_for_each_entry(tk, to_kill, nd)
> + if (tk->size_shift)
> + size = max(size, 1UL << tk->size_shift);
> + if (size) {
> + /*
> + * Unmap the largest mapping to avoid breaking up device-dax
> + * mappings which are constant size. The actual size of the
> + * mapping being torn down is communicated in siginfo, see
> + * kill_proc()
> + */
> + loff_t start = (index << PAGE_SHIFT) & ~(size - 1);
> +
> + unmap_mapping_range(mapping, start, size, 0);
> + }
> +
> + kill_procs(to_kill, flags & MF_MUST_KILL, false, pfn, flags);
> +}
> +
> +static int mf_generic_kill_procs(unsigned long long pfn, int flags,
> + struct dev_pagemap *pgmap)
> +{
> + struct page *page = pfn_to_page(pfn);
> + LIST_HEAD(to_kill);
> + dax_entry_t cookie;
> +
> + /*
> + * Prevent the inode from being freed while we are interrogating
> + * the address_space, typically this would be handled by
> + * lock_page(), but dax pages do not use the page lock. This
> + * also prevents changes to the mapping of this pfn until
> + * poison signaling is complete.
> + */
> + cookie = dax_lock_page(page);
> + if (!cookie)
> + return -EBUSY;
> +
> + if (hwpoison_filter(page))
> + return 0;
> +
> + if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
> + /*
> + * TODO: Handle HMM pages which may need coordination
> + * with device-side memory.
> + */
> + return -EBUSY;
> + }
> +
> + /*
> + * Use this flag as an indication that the dax page has been
> + * remapped UC to prevent speculative consumption of poison.
> + */
> + SetPageHWPoison(page);
> +
> + /*
> + * Unlike System-RAM there is no possibility to swap in a
> + * different physical page at a given virtual address, so all
> + * userspace consumption of ZONE_DEVICE memory necessitates
> + * SIGBUS (i.e. MF_MUST_KILL)
> + */
> + flags |= MF_ACTION_REQUIRED | MF_MUST_KILL;
> + collect_procs(page, &to_kill, true);
> +
> + unmap_and_kill(&to_kill, pfn, page->mapping, page->index, flags);
> + dax_unlock_page(page, cookie);
> + return 0;
> +}
> +
> static int memory_failure_hugetlb(unsigned long pfn, int flags)
> {
> struct page *p = pfn_to_page(pfn);
> @@ -1519,12 +1592,8 @@ static int memory_failure_dev_pagemap(unsigned long
> pfn, int flags,
> struct dev_pagemap *pgmap)
> {
> struct page *page = pfn_to_page(pfn);
> - unsigned long size = 0;
> - struct to_kill *tk;
> LIST_HEAD(tokill);
> - int rc = -EBUSY;
> - loff_t start;
> - dax_entry_t cookie;
> + int rc = -ENXIO;
>
> if (flags & MF_COUNT_INCREASED)
> /*
> @@ -1533,67 +1602,10 @@ static int memory_failure_dev_pagemap(unsigned long
> pfn, int flags,
> put_page(page);
>
> /* device metadata space is not recoverable */
> - if (!pgmap_pfn_valid(pgmap, pfn)) {
> - rc = -ENXIO;
> - goto out;
> - }
> -
> - /*
> - * Prevent the inode from being freed while we are interrogating
> - * the address_space, typically this would be handled by
> - * lock_page(), but dax pages do not use the page lock. This
> - * also prevents changes to the mapping of this pfn until
> - * poison signaling is complete.
> - */
> - cookie = dax_lock_page(page);
> - if (!cookie)
> + if (!pgmap_pfn_valid(pgmap, pfn))
> goto out;
>
> - if (hwpoison_filter(page)) {
> - rc = 0;
> - goto unlock;
> - }
> -
> - if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
> - /*
> - * TODO: Handle HMM pages which may need coordination
> - * with device-side memory.
> - */
> - goto unlock;
[PATCH v7 3/8] mm: factor helpers for memory_failure_dev_pagemap
memory_failure_dev_pagemap code is a bit complex before introduce RMAP
feature for fsdax. So it is needed to factor some helper functions to
simplify these code.
Signed-off-by: Shiyang Ruan
---
mm/memory-failure.c | 140
1 file changed, 76 insertions(+), 64 deletions(-)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 54879c339024..8ff9b52823c0 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1430,6 +1430,79 @@ static int try_to_split_thp_page(struct page *page,
const char *msg)
return 0;
}
+static void unmap_and_kill(struct list_head *to_kill, unsigned long pfn,
+ struct address_space *mapping, pgoff_t index, int flags)
+{
+ struct to_kill *tk;
+ unsigned long size = 0;
+
+ list_for_each_entry(tk, to_kill, nd)
+ if (tk->size_shift)
+ size = max(size, 1UL << tk->size_shift);
+ if (size) {
+ /*
+* Unmap the largest mapping to avoid breaking up device-dax
+* mappings which are constant size. The actual size of the
+* mapping being torn down is communicated in siginfo, see
+* kill_proc()
+*/
+ loff_t start = (index << PAGE_SHIFT) & ~(size - 1);
+
+ unmap_mapping_range(mapping, start, size, 0);
+ }
+
+ kill_procs(to_kill, flags & MF_MUST_KILL, false, pfn, flags);
+}
+
+static int mf_generic_kill_procs(unsigned long long pfn, int flags,
+ struct dev_pagemap *pgmap)
+{
+ struct page *page = pfn_to_page(pfn);
+ LIST_HEAD(to_kill);
+ dax_entry_t cookie;
+
+ /*
+* Prevent the inode from being freed while we are interrogating
+* the address_space, typically this would be handled by
+* lock_page(), but dax pages do not use the page lock. This
+* also prevents changes to the mapping of this pfn until
+* poison signaling is complete.
+*/
+ cookie = dax_lock_page(page);
+ if (!cookie)
+ return -EBUSY;
+
+ if (hwpoison_filter(page))
+ return 0;
+
+ if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
+ /*
+* TODO: Handle HMM pages which may need coordination
+* with device-side memory.
+*/
+ return -EBUSY;
+ }
+
+ /*
+* Use this flag as an indication that the dax page has been
+* remapped UC to prevent speculative consumption of poison.
+*/
+ SetPageHWPoison(page);
+
+ /*
+* Unlike System-RAM there is no possibility to swap in a
+* different physical page at a given virtual address, so all
+* userspace consumption of ZONE_DEVICE memory necessitates
+* SIGBUS (i.e. MF_MUST_KILL)
+*/
+ flags |= MF_ACTION_REQUIRED | MF_MUST_KILL;
+ collect_procs(page, &to_kill, true);
+
+ unmap_and_kill(&to_kill, pfn, page->mapping, page->index, flags);
+ dax_unlock_page(page, cookie);
+ return 0;
+}
+
static int memory_failure_hugetlb(unsigned long pfn, int flags)
{
struct page *p = pfn_to_page(pfn);
@@ -1519,12 +1592,8 @@ static int memory_failure_dev_pagemap(unsigned long pfn,
int flags,
struct dev_pagemap *pgmap)
{
struct page *page = pfn_to_page(pfn);
- unsigned long size = 0;
- struct to_kill *tk;
LIST_HEAD(tokill);
- int rc = -EBUSY;
- loff_t start;
- dax_entry_t cookie;
+ int rc = -ENXIO;
if (flags & MF_COUNT_INCREASED)
/*
@@ -1533,67 +1602,10 @@ static int memory_failure_dev_pagemap(unsigned long
pfn, int flags,
put_page(page);
/* device metadata space is not recoverable */
- if (!pgmap_pfn_valid(pgmap, pfn)) {
- rc = -ENXIO;
- goto out;
- }
-
- /*
-* Prevent the inode from being freed while we are interrogating
-* the address_space, typically this would be handled by
-* lock_page(), but dax pages do not use the page lock. This
-* also prevents changes to the mapping of this pfn until
-* poison signaling is complete.
-*/
- cookie = dax_lock_page(page);
- if (!cookie)
+ if (!pgmap_pfn_valid(pgmap, pfn))
goto out;
- if (hwpoison_filter(page)) {
- rc = 0;
- goto unlock;
- }
-
- if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
- /*
-* TODO: Handle HMM pages which may need coordination
-* with device-side memory.
-*/
- goto unlock;
- }
-
- /*
-* Use this flag as an indication that the dax page has been
-* remapped UC to prevent speculative consumption of poison.
-*/
- SetPageHWPoison(page);
-
- /*
-* U
