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Subject[PATCH] tty/vt: avoid high order pages allocation on GIO_UNIMAP ioctl
Date
GIO_UNIMAP can easily result in a high order allocation,
seen 6th order allocation on radeondrmfb:

fbcon: radeondrmfb (fb0) is primary device
Console: switching to colour frame buffer device 160x64
radeon 0000:01:05.0: fb0: radeondrmfb frame buffer device
WARNING: CPU: 0 PID: 78661 at mm/page_alloc.c:3532
__alloc_pages_nodemask+0x1b1/0x600
order 6 >= 3, gfp 0x40d0

The warning is generated by a debug patch.

At the same time it's safe to use kvmalloc() for allocation in
con_get_unimap(), so let's do the substitution.

And do the same for con_set_unimap().

Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
---
drivers/tty/vt/consolemap.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/vt/consolemap.c b/drivers/tty/vt/consolemap.c
index 7c7ada0b3ea0..b28aa0d289f8 100644
--- a/drivers/tty/vt/consolemap.c
+++ b/drivers/tty/vt/consolemap.c
@@ -542,7 +542,7 @@ int con_set_unimap(struct vc_data *vc, ushort ct, struct unipair __user *list)
if (!ct)
return 0;

- unilist = memdup_user(list, ct * sizeof(struct unipair));
+ unilist = vmemdup_user(list, ct * sizeof(struct unipair));
if (IS_ERR(unilist))
return PTR_ERR(unilist);

@@ -641,7 +641,7 @@ int con_set_unimap(struct vc_data *vc, ushort ct, struct unipair __user *list)

out_unlock:
console_unlock();
- kfree(unilist);
+ kvfree(unilist);
return err;
}

@@ -743,7 +743,7 @@ int con_get_unimap(struct vc_data *vc, ushort ct, ushort __user *uct, struct uni
struct uni_pagedir *p;
struct unipair *unilist;

- unilist = kmalloc_array(ct, sizeof(struct unipair), GFP_KERNEL);
+ unilist = kvmalloc_array(ct, sizeof(struct unipair), GFP_KERNEL);
if (!unilist)
return -ENOMEM;

@@ -775,7 +775,7 @@ int con_get_unimap(struct vc_data *vc, ushort ct, ushort __user *uct, struct uni
if (copy_to_user(list, unilist, min(ect, ct) * sizeof(struct unipair)))
ret = -EFAULT;
put_user(ect, uct);
- kfree(unilist);
+ kvfree(unilist);
return ret ? ret : (ect <= ct) ? 0 : -ENOMEM;
}

--
2.15.1
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