This is a note to let you know that I've just added the patch titled
udmabuf: revert 'Add support for mapping hugepages (v4)'
to the 6.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
udmabuf-revert-add-support-for-mapping-hugepages-v4.patch
and it can be found in the queue-6.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From b7cb3821905b79b6ed474fd5ba34d1e187649139 Mon Sep 17 00:00:00 2001
From: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Date: Thu, 8 Jun 2023 13:49:27 -0700
Subject: udmabuf: revert 'Add support for mapping hugepages (v4)'
From: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
commit b7cb3821905b79b6ed474fd5ba34d1e187649139 upstream.
This effectively reverts commit 16c243e99d33 ("udmabuf: Add support for
mapping hugepages (v4)"). Recently, Junxiao Chang found a BUG with page
map counting as described here [1]. This issue pointed out that the
udmabuf driver was making direct use of subpages of hugetlb pages. This
is not a good idea, and no other mm code attempts such use. In addition
to the mapcount issue, this also causes issues with hugetlb vmemmap
optimization and page poisoning.
For now, remove hugetlb support.
If udmabuf wants to be used on hugetlb mappings, it should be changed to
only use complete hugetlb pages. This will require different alignment
and size requirements on the UDMABUF_CREATE API.
[1] https://lore.kernel.org/linux-mm/20230512072036.1027784-1-junxiao.chang@xxxxxxxxx/
Link: https://lkml.kernel.org/r/20230608204927.88711-1-mike.kravetz@xxxxxxxxxx
Fixes: 16c243e99d33 ("udmabuf: Add support for mapping hugepages (v4)")
Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Acked-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Acked-by: Vivek Kasireddy <vivek.kasireddy@xxxxxxxxx>
Acked-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Dongwon Kim <dongwon.kim@xxxxxxxxx>
Cc: James Houghton <jthoughton@xxxxxxxxxx>
Cc: Jerome Marchand <jmarchan@xxxxxxxxxx>
Cc: Junxiao Chang <junxiao.chang@xxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/dma-buf/udmabuf.c | 47 +++++-----------------------------------------
1 file changed, 6 insertions(+), 41 deletions(-)
--- a/drivers/dma-buf/udmabuf.c
+++ b/drivers/dma-buf/udmabuf.c
@@ -12,7 +12,6 @@
#include <linux/shmem_fs.h>
#include <linux/slab.h>
#include <linux/udmabuf.h>
-#include <linux/hugetlb.h>
#include <linux/vmalloc.h>
#include <linux/iosys-map.h>
@@ -207,9 +206,7 @@ static long udmabuf_create(struct miscde
struct udmabuf *ubuf;
struct dma_buf *buf;
pgoff_t pgoff, pgcnt, pgidx, pgbuf = 0, pglimit;
- struct page *page, *hpage = NULL;
- pgoff_t subpgoff, maxsubpgs;
- struct hstate *hpstate;
+ struct page *page;
int seals, ret = -EINVAL;
u32 i, flags;
@@ -245,7 +242,7 @@ static long udmabuf_create(struct miscde
if (!memfd)
goto err;
mapping = memfd->f_mapping;
- if (!shmem_mapping(mapping) && !is_file_hugepages(memfd))
+ if (!shmem_mapping(mapping))
goto err;
seals = memfd_fcntl(memfd, F_GET_SEALS, 0);
if (seals == -EINVAL)
@@ -256,48 +253,16 @@ static long udmabuf_create(struct miscde
goto err;
pgoff = list[i].offset >> PAGE_SHIFT;
pgcnt = list[i].size >> PAGE_SHIFT;
- if (is_file_hugepages(memfd)) {
- hpstate = hstate_file(memfd);
- pgoff = list[i].offset >> huge_page_shift(hpstate);
- subpgoff = (list[i].offset &
- ~huge_page_mask(hpstate)) >> PAGE_SHIFT;
- maxsubpgs = huge_page_size(hpstate) >> PAGE_SHIFT;
- }
for (pgidx = 0; pgidx < pgcnt; pgidx++) {
- if (is_file_hugepages(memfd)) {
- if (!hpage) {
- hpage = find_get_page_flags(mapping, pgoff,
- FGP_ACCESSED);
- if (!hpage) {
- ret = -EINVAL;
- goto err;
- }
- }
- page = hpage + subpgoff;
- get_page(page);
- subpgoff++;
- if (subpgoff == maxsubpgs) {
- put_page(hpage);
- hpage = NULL;
- subpgoff = 0;
- pgoff++;
- }
- } else {
- page = shmem_read_mapping_page(mapping,
- pgoff + pgidx);
- if (IS_ERR(page)) {
- ret = PTR_ERR(page);
- goto err;
- }
+ page = shmem_read_mapping_page(mapping, pgoff + pgidx);
+ if (IS_ERR(page)) {
+ ret = PTR_ERR(page);
+ goto err;
}
ubuf->pages[pgbuf++] = page;
}
fput(memfd);
memfd = NULL;
- if (hpage) {
- put_page(hpage);
- hpage = NULL;
- }
}
exp_info.ops = &udmabuf_ops;
Patches currently in stable-queue which might be from mike.kravetz@xxxxxxxxxx are
queue-6.3/udmabuf-revert-add-support-for-mapping-hugepages-v4.patch
