[PATCH v2 0/1] s390/crash: allow multi-segment iterators

[PATCH v2 0/1] s390/crash: allow multi-segment iterators

[Alexander Gordeev]

Unlike other architectures s390 can not use copyout() and memcopy() for
accessing memory and thus using copy_to_iter() now is not possible. But
a fix is needed, since 'cp' routine as 'core_collector' for kdump service
initiates multi-segment iterator.

The reason iterate_iovec() and __iterate_and_advance() macros copied from
lib/iov_iter.c (thus introducing redundancy) is to avoid custom iterator-
treating in s390 code. I doubt these macros could be turned public (i.e
with a follow-up patch), so the intention is to do it like _copy_to_iter()
does.

Changes since v1:
  - number of bytes left to copy on fail fixed;

Alexander Gordeev (1):
  s390/crash: allow multi-segment iterators

 arch/s390/kernel/crash_dump.c | 65 +++++++++++++++++++++++++++--------
 1 file changed, 50 insertions(+), 15 deletions(-)

-- 
2.34.1

[PATCH v2 1/1] s390/crash: allow multi-segment iterators

[Alexander Gordeev]

Rework copy_oldmem_page() to allow multi-segment iterators.
Reuse existing iterate_iovec macro as is and only relevant
bits from __iterate_and_advance macro.

Fixes: 49b11524d648 ("s390/crash: add missing iterator advance in copy_oldmem_page())
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
---
 arch/s390/kernel/crash_dump.c | 65 +++++++++++++++++++++++++++--------
 1 file changed, 50 insertions(+), 15 deletions(-)

diff --git a/arch/s390/kernel/crash_dump.c b/arch/s390/kernel/crash_dump.c
index 28124d0fa1d5..cc1586d64ce2 100644
--- a/arch/s390/kernel/crash_dump.c
+++ b/arch/s390/kernel/crash_dump.c
@@ -210,6 +210,52 @@ static int copy_oldmem_user(void __user *dst, unsigned long src, size_t count)
 	return 0;
 }
 
+#define iterate_iovec(i, n, base, len, off, __p, STEP) {	\
+	size_t off = 0;						\
+	size_t skip = i->iov_offset;				\
+	do {							\
+		len = min(n, __p->iov_len - skip);		\
+		if (likely(len)) {				\
+			base = __p->iov_base + skip;		\
+			len -= (STEP);				\
+			off += len;				\
+			skip += len;				\
+			n -= len;				\
+			if (skip < __p->iov_len)		\
+				break;				\
+		}						\
+		__p++;						\
+		skip = 0;					\
+	} while (n);						\
+	i->iov_offset = skip;					\
+	n = off;						\
+}
+
+#define __iterate_and_advance(i, n, base, len, off, I, K) {	\
+	if (unlikely(i->count < n))				\
+		n = i->count;					\
+	if (likely(n)) {					\
+		if (likely(iter_is_iovec(i))) {			\
+			const struct iovec *iov = i->iov;	\
+			void __user *base;			\
+			size_t len;				\
+			iterate_iovec(i, n, base, len, off,	\
+						iov, (I))	\
+			i->nr_segs -= iov - i->iov;		\
+			i->iov = iov;				\
+		} else if (iov_iter_is_kvec(i)) {		\
+			const struct kvec *kvec = i->kvec;	\
+			void *base;				\
+			size_t len;				\
+			iterate_iovec(i, n, base, len, off,	\
+						kvec, (K))	\
+			i->nr_segs -= kvec - i->kvec;		\
+			i->kvec = kvec;				\
+		}						\
+		i->count -= n;					\
+	}							\
+}
+
 /*
  * Copy one page from "oldmem"
  */
@@ -217,25 +263,14 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, size_t csize,
 			 unsigned long offset)
 {
 	unsigned long src;
-	int rc;
 
 	if (!(iter_is_iovec(iter) || iov_iter_is_kvec(iter)))
 		return -EINVAL;
-	/* Multi-segment iterators are not supported */
-	if (iter->nr_segs > 1)
-		return -EINVAL;
-	if (!csize)
-		return 0;
 	src = pfn_to_phys(pfn) + offset;
-
-	/* XXX: pass the iov_iter down to a common function */
-	if (iter_is_iovec(iter))
-		rc = copy_oldmem_user(iter->iov->iov_base, src, csize);
-	else
-		rc = copy_oldmem_kernel(iter->kvec->iov_base, src, csize);
-	if (rc < 0)
-		return rc;
-	iov_iter_advance(iter, csize);
+	__iterate_and_advance(iter, csize, base, len, off,
+		({ copy_oldmem_user(base, src + off, len) < 0 ? len : 0; }),
+		({ copy_oldmem_kernel(base, src + off, len) < 0 ? len : 0; })
+	)
 	return csize;
 }
 
-- 
2.34.1

Re: [PATCH v2 1/1] s390/crash: allow multi-segment iterators

[Al Viro]

On Thu, Jul 07, 2022 at 08:01:15AM +0200, Alexander Gordeev wrote:
> Rework copy_oldmem_page() to allow multi-segment iterators.
> Reuse existing iterate_iovec macro as is and only relevant
> bits from __iterate_and_advance macro.
> 
> Fixes: 49b11524d648 ("s390/crash: add missing iterator advance in copy_oldmem_page())
> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

To be followed by duplication of every change ever done to those macros?
Hell, no.  Do it the same way it's done for that _copy_from_iter_flushcache()
thing - i.e. an ifdef in lib/iov_iter.c and no duplication of that forest of
macros.

Re: [PATCH v2 1/1] s390/crash: allow multi-segment iterators

[Matthew Wilcox]

On Thu, Jul 07, 2022 at 08:01:15AM +0200, Alexander Gordeev wrote:
> Rework copy_oldmem_page() to allow multi-segment iterators.
> Reuse existing iterate_iovec macro as is and only relevant
> bits from __iterate_and_advance macro.

Or do it properly?

You should probably put a mutex around all of this because if you have two
threads accessing the hsa at the same time, they'll use the same buffer.
But that's a pre-existing problem.  I also fixed the pre-existing bug
where you were using 'count' when you meant to use 'len'.

Uncompiled.  You might need to include <linux/uio.h> somewhere.

diff --git a/arch/s390/include/asm/sclp.h b/arch/s390/include/asm/sclp.h
index 236b34b75ddb..d8b4c526e0f0 100644
--- a/arch/s390/include/asm/sclp.h
+++ b/arch/s390/include/asm/sclp.h
@@ -143,7 +143,7 @@ int sclp_ap_configure(u32 apid);
 int sclp_ap_deconfigure(u32 apid);
 int sclp_pci_report(struct zpci_report_error_header *report, u32 fh, u32 fid);
 int memcpy_hsa_kernel(void *dest, unsigned long src, size_t count);
-int memcpy_hsa_user(void __user *dest, unsigned long src, size_t count);
+int memcpy_hsa_iter(struct iov_iter *iter, unsigned long src, size_t count);
 void sclp_ocf_cpc_name_copy(char *dst);
 
 static inline int sclp_get_core_info(struct sclp_core_info *info, int early)
diff --git a/arch/s390/kernel/crash_dump.c b/arch/s390/kernel/crash_dump.c
index 28124d0fa1d5..6e4dde377f8e 100644
--- a/arch/s390/kernel/crash_dump.c
+++ b/arch/s390/kernel/crash_dump.c
@@ -130,53 +130,11 @@ static inline void *load_real_addr(void *addr)
 	return (void *)real_addr;
 }
 
-/*
- * Copy memory of the old, dumped system to a kernel space virtual address
- */
-int copy_oldmem_kernel(void *dst, unsigned long src, size_t count)
-{
-	unsigned long len;
-	void *ra;
-	int rc;
-
-	while (count) {
-		if (!oldmem_data.start && src < sclp.hsa_size) {
-			/* Copy from zfcp/nvme dump HSA area */
-			len = min(count, sclp.hsa_size - src);
-			rc = memcpy_hsa_kernel(dst, src, len);
-			if (rc)
-				return rc;
-		} else {
-			/* Check for swapped kdump oldmem areas */
-			if (oldmem_data.start && src - oldmem_data.start < oldmem_data.size) {
-				src -= oldmem_data.start;
-				len = min(count, oldmem_data.size - src);
-			} else if (oldmem_data.start && src < oldmem_data.size) {
-				len = min(count, oldmem_data.size - src);
-				src += oldmem_data.start;
-			} else {
-				len = count;
-			}
-			if (is_vmalloc_or_module_addr(dst)) {
-				ra = load_real_addr(dst);
-				len = min(PAGE_SIZE - offset_in_page(ra), len);
-			} else {
-				ra = dst;
-			}
-			if (memcpy_real(ra, src, len))
-				return -EFAULT;
-		}
-		dst += len;
-		src += len;
-		count -= len;
-	}
-	return 0;
-}
-
 /*
  * Copy memory of the old, dumped system to a user space virtual address
  */
-static int copy_oldmem_user(void __user *dst, unsigned long src, size_t count)
+static int copy_oldmem_iter(struct iov_iter *iter, unsigned long src,
+		size_t count)
 {
 	unsigned long len;
 	int rc;
@@ -185,7 +143,7 @@ static int copy_oldmem_user(void __user *dst, unsigned long src, size_t count)
 		if (!oldmem_data.start && src < sclp.hsa_size) {
 			/* Copy from zfcp/nvme dump HSA area */
 			len = min(count, sclp.hsa_size - src);
-			rc = memcpy_hsa_user(dst, src, len);
+			rc = memcpy_hsa_iter(iter, src, len);
 			if (rc)
 				return rc;
 		} else {
@@ -199,8 +157,8 @@ static int copy_oldmem_user(void __user *dst, unsigned long src, size_t count)
 			} else {
 				len = count;
 			}
-			rc = copy_to_user_real(dst, src, count);
-			if (rc)
+			rc = copy_to_iter(iter, src, len);
+			if (rc != len)
 				return rc;
 		}
 		dst += len;
@@ -219,23 +177,13 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, size_t csize,
 	unsigned long src;
 	int rc;
 
-	if (!(iter_is_iovec(iter) || iov_iter_is_kvec(iter)))
-		return -EINVAL;
-	/* Multi-segment iterators are not supported */
-	if (iter->nr_segs > 1)
-		return -EINVAL;
 	if (!csize)
 		return 0;
 	src = pfn_to_phys(pfn) + offset;
 
-	/* XXX: pass the iov_iter down to a common function */
-	if (iter_is_iovec(iter))
-		rc = copy_oldmem_user(iter->iov->iov_base, src, csize);
-	else
-		rc = copy_oldmem_kernel(iter->kvec->iov_base, src, csize);
+	rc = copy_oldmem_iter(iter, src, csize);
 	if (rc < 0)
 		return rc;
-	iov_iter_advance(iter, csize);
 	return csize;
 }
 
diff --git a/drivers/s390/char/zcore.c b/drivers/s390/char/zcore.c
index 516783ba950f..26125718f3e0 100644
--- a/drivers/s390/char/zcore.c
+++ b/drivers/s390/char/zcore.c
@@ -59,7 +59,7 @@ static char hsa_buf[PAGE_SIZE] __aligned(PAGE_SIZE);
  * @src:   Start address within HSA where data should be copied
  * @count: Size of buffer, which should be copied
  */
-int memcpy_hsa_user(void __user *dest, unsigned long src, size_t count)
+int memcpy_hsa_iter(struct iov_iter *iter, unsigned long src, size_t count)
 {
 	unsigned long offset, bytes;
 
@@ -73,10 +73,9 @@ int memcpy_hsa_user(void __user *dest, unsigned long src, size_t count)
 		}
 		offset = src % PAGE_SIZE;
 		bytes = min(PAGE_SIZE - offset, count);
-		if (copy_to_user(dest, hsa_buf + offset, bytes))
+		if (copy_to_iter(hsa_buf + offset, bytes, iter) != bytes)
 			return -EFAULT;
 		src += bytes;
-		dest += bytes;
 		count -= bytes;
 	}
 	return 0;

Re: [PATCH v2 1/1] s390/crash: allow multi-segment iterators

[Al Viro]

On Thu, Jul 07, 2022 at 01:54:22PM +0100, Matthew Wilcox wrote:
> On Thu, Jul 07, 2022 at 08:01:15AM +0200, Alexander Gordeev wrote:
> > Rework copy_oldmem_page() to allow multi-segment iterators.
> > Reuse existing iterate_iovec macro as is and only relevant
> > bits from __iterate_and_advance macro.
> 
> Or do it properly?

Or that...

> You should probably put a mutex around all of this because if you have two
> threads accessing the hsa at the same time, they'll use the same buffer.
> But that's a pre-existing problem.  I also fixed the pre-existing bug
> where you were using 'count' when you meant to use 'len'.
> 
> Uncompiled.  You might need to include <linux/uio.h> somewhere.
> 
> diff --git a/arch/s390/include/asm/sclp.h b/arch/s390/include/asm/sclp.h
> index 236b34b75ddb..d8b4c526e0f0 100644
> --- a/arch/s390/include/asm/sclp.h
> +++ b/arch/s390/include/asm/sclp.h
> @@ -143,7 +143,7 @@ int sclp_ap_configure(u32 apid);
>  int sclp_ap_deconfigure(u32 apid);
>  int sclp_pci_report(struct zpci_report_error_header *report, u32 fh, u32 fid);
>  int memcpy_hsa_kernel(void *dest, unsigned long src, size_t count);
> -int memcpy_hsa_user(void __user *dest, unsigned long src, size_t count);
> +int memcpy_hsa_iter(struct iov_iter *iter, unsigned long src, size_t count);
>  void sclp_ocf_cpc_name_copy(char *dst);
>  
>  static inline int sclp_get_core_info(struct sclp_core_info *info, int early)
> diff --git a/arch/s390/kernel/crash_dump.c b/arch/s390/kernel/crash_dump.c
> index 28124d0fa1d5..6e4dde377f8e 100644
> --- a/arch/s390/kernel/crash_dump.c
> +++ b/arch/s390/kernel/crash_dump.c
> @@ -130,53 +130,11 @@ static inline void *load_real_addr(void *addr)
>  	return (void *)real_addr;
>  }
>  
> -/*
> - * Copy memory of the old, dumped system to a kernel space virtual address
> - */
> -int copy_oldmem_kernel(void *dst, unsigned long src, size_t count)
> -{
> -	unsigned long len;
> -	void *ra;
> -	int rc;
> -
> -	while (count) {
> -		if (!oldmem_data.start && src < sclp.hsa_size) {
> -			/* Copy from zfcp/nvme dump HSA area */
> -			len = min(count, sclp.hsa_size - src);
> -			rc = memcpy_hsa_kernel(dst, src, len);
> -			if (rc)
> -				return rc;
> -		} else {
> -			/* Check for swapped kdump oldmem areas */
> -			if (oldmem_data.start && src - oldmem_data.start < oldmem_data.size) {
> -				src -= oldmem_data.start;
> -				len = min(count, oldmem_data.size - src);
> -			} else if (oldmem_data.start && src < oldmem_data.size) {
> -				len = min(count, oldmem_data.size - src);
> -				src += oldmem_data.start;
> -			} else {
> -				len = count;
> -			}
> -			if (is_vmalloc_or_module_addr(dst)) {
> -				ra = load_real_addr(dst);
> -				len = min(PAGE_SIZE - offset_in_page(ra), len);
> -			} else {
> -				ra = dst;
> -			}
> -			if (memcpy_real(ra, src, len))
> -				return -EFAULT;
> -		}
> -		dst += len;
> -		src += len;
> -		count -= len;
> -	}
> -	return 0;
> -}
> -
>  /*
>   * Copy memory of the old, dumped system to a user space virtual address
>   */
> -static int copy_oldmem_user(void __user *dst, unsigned long src, size_t count)
> +static int copy_oldmem_iter(struct iov_iter *iter, unsigned long src,
> +		size_t count)
>  {
>  	unsigned long len;
>  	int rc;
> @@ -185,7 +143,7 @@ static int copy_oldmem_user(void __user *dst, unsigned long src, size_t count)
>  		if (!oldmem_data.start && src < sclp.hsa_size) {
>  			/* Copy from zfcp/nvme dump HSA area */
>  			len = min(count, sclp.hsa_size - src);
> -			rc = memcpy_hsa_user(dst, src, len);
> +			rc = memcpy_hsa_iter(iter, src, len);
>  			if (rc)
>  				return rc;
>  		} else {
> @@ -199,8 +157,8 @@ static int copy_oldmem_user(void __user *dst, unsigned long src, size_t count)
>  			} else {
>  				len = count;
>  			}
> -			rc = copy_to_user_real(dst, src, count);
> -			if (rc)
> +			rc = copy_to_iter(iter, src, len);
> +			if (rc != len)
>  				return rc;
>  		}
>  		dst += len;
> @@ -219,23 +177,13 @@ ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, size_t csize,
>  	unsigned long src;
>  	int rc;
>  
> -	if (!(iter_is_iovec(iter) || iov_iter_is_kvec(iter)))
> -		return -EINVAL;
> -	/* Multi-segment iterators are not supported */
> -	if (iter->nr_segs > 1)
> -		return -EINVAL;
>  	if (!csize)
>  		return 0;
>  	src = pfn_to_phys(pfn) + offset;
>  
> -	/* XXX: pass the iov_iter down to a common function */
> -	if (iter_is_iovec(iter))
> -		rc = copy_oldmem_user(iter->iov->iov_base, src, csize);
> -	else
> -		rc = copy_oldmem_kernel(iter->kvec->iov_base, src, csize);
> +	rc = copy_oldmem_iter(iter, src, csize);
>  	if (rc < 0)
>  		return rc;
> -	iov_iter_advance(iter, csize);
>  	return csize;
>  }
>  
> diff --git a/drivers/s390/char/zcore.c b/drivers/s390/char/zcore.c
> index 516783ba950f..26125718f3e0 100644
> --- a/drivers/s390/char/zcore.c
> +++ b/drivers/s390/char/zcore.c
> @@ -59,7 +59,7 @@ static char hsa_buf[PAGE_SIZE] __aligned(PAGE_SIZE);
>   * @src:   Start address within HSA where data should be copied
>   * @count: Size of buffer, which should be copied
>   */
> -int memcpy_hsa_user(void __user *dest, unsigned long src, size_t count)
> +int memcpy_hsa_iter(struct iov_iter *iter, unsigned long src, size_t count)
>  {
>  	unsigned long offset, bytes;
>  
> @@ -73,10 +73,9 @@ int memcpy_hsa_user(void __user *dest, unsigned long src, size_t count)
>  		}
>  		offset = src % PAGE_SIZE;
>  		bytes = min(PAGE_SIZE - offset, count);
> -		if (copy_to_user(dest, hsa_buf + offset, bytes))
> +		if (copy_to_iter(hsa_buf + offset, bytes, iter) != bytes)
>  			return -EFAULT;

Umm...  Then you want iov_iter_revert() on short copy...

Re: [PATCH v2 1/1] s390/crash: allow multi-segment iterators

[Matthew Wilcox]

On Thu, Jul 07, 2022 at 02:31:44PM +0100, Al Viro wrote:
> > @@ -73,10 +73,9 @@ int memcpy_hsa_user(void __user *dest, unsigned long src, size_t count)
> >  		}
> >  		offset = src % PAGE_SIZE;
> >  		bytes = min(PAGE_SIZE - offset, count);
> > -		if (copy_to_user(dest, hsa_buf + offset, bytes))
> > +		if (copy_to_iter(hsa_buf + offset, bytes, iter) != bytes)
> >  			return -EFAULT;
> 
> Umm...  Then you want iov_iter_revert() on short copy...

... maybe better to change the calling convention to return the short
write and have the caller do it if they care?

Re: [PATCH v2 1/1] s390/crash: allow multi-segment iterators

[Alexander Gordeev]

On Thu, Jul 07, 2022 at 01:54:22PM +0100, Matthew Wilcox wrote:
> On Thu, Jul 07, 2022 at 08:01:15AM +0200, Alexander Gordeev wrote:
> > Rework copy_oldmem_page() to allow multi-segment iterators.
> > Reuse existing iterate_iovec macro as is and only relevant
> > bits from __iterate_and_advance macro.

> Or do it properly?
> 
> You should probably put a mutex around all of this because if you have two
> threads accessing the hsa at the same time, they'll use the same buffer.
> But that's a pre-existing problem.  I also fixed the pre-existing bug
> where you were using 'count' when you meant to use 'len'.

Thank you, Matthew!

Would you mind being added with Suggested-by to the fix(es)?

> Uncompiled.  You might need to include <linux/uio.h> somewhere.

The problem with your suggestion is memcpy()/copyout() might fail
since pages to be copied are not guaranteed to be mapped on s390.
For that we use s390-specific memcpy_real() routine that only takes
physical addresses and bypasses paging altogether (I added some
comments to the removed code, just in case you are interested).

Yet, I am still going to reuse and extend your approach and
hopefully come up with something soon.

As a side note - there is an intention to make things more like
others, but not just right now.

> diff --git a/arch/s390/include/asm/sclp.h b/arch/s390/include/asm/sclp.h
> index 236b34b75ddb..d8b4c526e0f0 100644
> --- a/arch/s390/include/asm/sclp.h
> +++ b/arch/s390/include/asm/sclp.h
> @@ -143,7 +143,7 @@ int sclp_ap_configure(u32 apid);
>  int sclp_ap_deconfigure(u32 apid);
>  int sclp_pci_report(struct zpci_report_error_header *report, u32 fh, u32 fid);
>  int memcpy_hsa_kernel(void *dest, unsigned long src, size_t count);
> -int memcpy_hsa_user(void __user *dest, unsigned long src, size_t count);
> +int memcpy_hsa_iter(struct iov_iter *iter, unsigned long src, size_t count);
>  void sclp_ocf_cpc_name_copy(char *dst);
>  
>  static inline int sclp_get_core_info(struct sclp_core_info *info, int early)
> diff --git a/arch/s390/kernel/crash_dump.c b/arch/s390/kernel/crash_dump.c
> index 28124d0fa1d5..6e4dde377f8e 100644
> --- a/arch/s390/kernel/crash_dump.c
> +++ b/arch/s390/kernel/crash_dump.c
> @@ -130,53 +130,11 @@ static inline void *load_real_addr(void *addr)
>  	return (void *)real_addr;
>  }
>  
> -/*
> - * Copy memory of the old, dumped system to a kernel space virtual address
> - */
> -int copy_oldmem_kernel(void *dst, unsigned long src, size_t count)
> -{
> -	unsigned long len;
> -	void *ra;
> -	int rc;
> -
> -	while (count) {
> -		if (!oldmem_data.start && src < sclp.hsa_size) {
> -			/* Copy from zfcp/nvme dump HSA area */
> -			len = min(count, sclp.hsa_size - src);
> -			rc = memcpy_hsa_kernel(dst, src, len);
> -			if (rc)
> -				return rc;
> -		} else {
> -			/* Check for swapped kdump oldmem areas */
> -			if (oldmem_data.start && src - oldmem_data.start < oldmem_data.size) {
> -				src -= oldmem_data.start;
> -				len = min(count, oldmem_data.size - src);
> -			} else if (oldmem_data.start && src < oldmem_data.size) {
> -				len = min(count, oldmem_data.size - src);
> -				src += oldmem_data.start;
> -			} else {
> -				len = count;
> -			}
> -			if (is_vmalloc_or_module_addr(dst)) {

There is no 1:1 match between vmalloc/module addresses.

> -				ra = load_real_addr(dst);

load_real_addr() obtains the physical addresses from a virtual one to be
able passing it to memcpy_real(). 

> -				len = min(PAGE_SIZE - offset_in_page(ra), len);
> -			} else {
> -				ra = dst;

Here a virtual address matches the physical one and thus - good to go.

> -			}
> -			if (memcpy_real(ra, src, len))
> -				return -EFAULT;

As the source address might be unmapped, copy_to_iter()->memcpy()
would not be safe to use here.

> -		}
> -		dst += len;
> -		src += len;
> -		count -= len;
> -	}
> -	return 0;
> -}
> -
>  /*
>   * Copy memory of the old, dumped system to a user space virtual address
>   */
> -static int copy_oldmem_user(void __user *dst, unsigned long src, size_t count)
> +static int copy_oldmem_iter(struct iov_iter *iter, unsigned long src,
> +		size_t count)
>  {
>  	unsigned long len;
>  	int rc;
> @@ -185,7 +143,7 @@ static int copy_oldmem_user(void __user *dst, unsigned long src, size_t count)
>  		if (!oldmem_data.start && src < sclp.hsa_size) {
>  			/* Copy from zfcp/nvme dump HSA area */
>  			len = min(count, sclp.hsa_size - src);
> -			rc = memcpy_hsa_user(dst, src, len);
> +			rc = memcpy_hsa_iter(iter, src, len);
>  			if (rc)
>  				return rc;
>  		} else {
> @@ -199,8 +157,8 @@ static int copy_oldmem_user(void __user *dst, unsigned long src, size_t count)
>  			} else {
>  				len = count;
>  			}
> -			rc = copy_to_user_real(dst, src, count);
> -			if (rc)
> +			rc = copy_to_iter(iter, src, len);

As the source address might be unmapped, copy_to_iter()->raw_copy_to_user()
is not safe to use here.

> +			if (rc != len)
>  				return rc;
>  		}
>  		dst += len;

Thanks!