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authorLinus Torvalds <torvalds@linux-foundation.org>2016-10-19 08:39:47 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-10-19 08:39:47 -0700
commit63ae602cea637ee4a6490d940c0da5d78bd0bbe0 (patch)
tree5da1eec3756fec9d62455c498442944a7f35149b /fs
parent1a1891d762d6e64daf07b5be4817e3fbb29e3c59 (diff)
parentf307ab6dcea03f9d8e4d70508fd7d1ca57cfa7f9 (diff)
downloadlinux-63ae602cea637ee4a6490d940c0da5d78bd0bbe0.tar.bz2
Merge branch 'gup_flag-cleanups'
Merge the gup_flags cleanups from Lorenzo Stoakes: "This patch series adjusts functions in the get_user_pages* family such that desired FOLL_* flags are passed as an argument rather than implied by flags. The purpose of this change is to make the use of FOLL_FORCE explicit so it is easier to grep for and clearer to callers that this flag is being used. The use of FOLL_FORCE is an issue as it overrides missing VM_READ/VM_WRITE flags for the VMA whose pages we are reading from/writing to, which can result in surprising behaviour. The patch series came out of the discussion around commit 38e088546522 ("mm: check VMA flags to avoid invalid PROT_NONE NUMA balancing"), which addressed a BUG_ON() being triggered when a page was faulted in with PROT_NONE set but having been overridden by FOLL_FORCE. do_numa_page() was run on the assumption the page _must_ be one marked for NUMA node migration as an actual PROT_NONE page would have been dealt with prior to this code path, however FOLL_FORCE introduced a situation where this assumption did not hold. See https://marc.info/?l=linux-mm&m=147585445805166 for the patch proposal" Additionally, there's a fix for an ancient bug related to FOLL_FORCE and FOLL_WRITE by me. [ This branch was rebased recently to add a few more acked-by's and reviewed-by's ] * gup_flag-cleanups: mm: replace access_process_vm() write parameter with gup_flags mm: replace access_remote_vm() write parameter with gup_flags mm: replace __access_remote_vm() write parameter with gup_flags mm: replace get_user_pages_remote() write/force parameters with gup_flags mm: replace get_user_pages() write/force parameters with gup_flags mm: replace get_vaddr_frames() write/force parameters with gup_flags mm: replace get_user_pages_locked() write/force parameters with gup_flags mm: replace get_user_pages_unlocked() write/force parameters with gup_flags mm: remove write/force parameters from __get_user_pages_unlocked() mm: remove write/force parameters from __get_user_pages_locked() mm: remove gup_flags FOLL_WRITE games from __get_user_pages()
Diffstat (limited to 'fs')
-rw-r--r--fs/exec.c9
-rw-r--r--fs/proc/base.c19
2 files changed, 20 insertions, 8 deletions
diff --git a/fs/exec.c b/fs/exec.c
index 6fcfb3f7b137..4e497b9ee71e 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -191,6 +191,7 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
{
struct page *page;
int ret;
+ unsigned int gup_flags = FOLL_FORCE;
#ifdef CONFIG_STACK_GROWSUP
if (write) {
@@ -199,12 +200,16 @@ static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
return NULL;
}
#endif
+
+ if (write)
+ gup_flags |= FOLL_WRITE;
+
/*
* We are doing an exec(). 'current' is the process
* doing the exec and bprm->mm is the new process's mm.
*/
- ret = get_user_pages_remote(current, bprm->mm, pos, 1, write,
- 1, &page, NULL);
+ ret = get_user_pages_remote(current, bprm->mm, pos, 1, gup_flags,
+ &page, NULL);
if (ret <= 0)
return NULL;
diff --git a/fs/proc/base.c b/fs/proc/base.c
index c2964d890c9a..8e654468ab67 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -252,7 +252,7 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
* Inherently racy -- command line shares address space
* with code and data.
*/
- rv = access_remote_vm(mm, arg_end - 1, &c, 1, 0);
+ rv = access_remote_vm(mm, arg_end - 1, &c, 1, FOLL_FORCE);
if (rv <= 0)
goto out_free_page;
@@ -270,7 +270,8 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
int nr_read;
_count = min3(count, len, PAGE_SIZE);
- nr_read = access_remote_vm(mm, p, page, _count, 0);
+ nr_read = access_remote_vm(mm, p, page, _count,
+ FOLL_FORCE);
if (nr_read < 0)
rv = nr_read;
if (nr_read <= 0)
@@ -305,7 +306,8 @@ static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
bool final;
_count = min3(count, len, PAGE_SIZE);
- nr_read = access_remote_vm(mm, p, page, _count, 0);
+ nr_read = access_remote_vm(mm, p, page, _count,
+ FOLL_FORCE);
if (nr_read < 0)
rv = nr_read;
if (nr_read <= 0)
@@ -354,7 +356,8 @@ skip_argv:
bool final;
_count = min3(count, len, PAGE_SIZE);
- nr_read = access_remote_vm(mm, p, page, _count, 0);
+ nr_read = access_remote_vm(mm, p, page, _count,
+ FOLL_FORCE);
if (nr_read < 0)
rv = nr_read;
if (nr_read <= 0)
@@ -832,6 +835,7 @@ static ssize_t mem_rw(struct file *file, char __user *buf,
unsigned long addr = *ppos;
ssize_t copied;
char *page;
+ unsigned int flags = FOLL_FORCE;
if (!mm)
return 0;
@@ -844,6 +848,9 @@ static ssize_t mem_rw(struct file *file, char __user *buf,
if (!atomic_inc_not_zero(&mm->mm_users))
goto free;
+ if (write)
+ flags |= FOLL_WRITE;
+
while (count > 0) {
int this_len = min_t(int, count, PAGE_SIZE);
@@ -852,7 +859,7 @@ static ssize_t mem_rw(struct file *file, char __user *buf,
break;
}
- this_len = access_remote_vm(mm, addr, page, this_len, write);
+ this_len = access_remote_vm(mm, addr, page, this_len, flags);
if (!this_len) {
if (!copied)
copied = -EIO;
@@ -965,7 +972,7 @@ static ssize_t environ_read(struct file *file, char __user *buf,
this_len = min(max_len, this_len);
retval = access_remote_vm(mm, (env_start + src),
- page, this_len, 0);
+ page, this_len, FOLL_FORCE);
if (retval <= 0) {
ret = retval;