![Daniel Jordan](/assets/img/avatar_default.png)
locked_vm accounting is done roughly the same way in five places, so unify them in a helper. Include the helper's caller in the debug print to distinguish between callsites. Error codes stay the same, so user-visible behavior does too. The one exception is that the -EPERM case in tce_account_locked_vm is removed because Alexey has never seen it triggered. [daniel.m.jordan@oracle.com: v3] Link: http://lkml.kernel.org/r/20190529205019.20927-1-daniel.m.jordan@oracle.com [sfr@canb.auug.org.au: fix mm/util.c] Link: http://lkml.kernel.org/r/20190524175045.26897-1-daniel.m.jordan@oracle.com Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Tested-by: Alexey Kardashevskiy <aik@ozlabs.ru> Acked-by: Alex Williamson <alex.williamson@redhat.com> Cc: Alan Tull <atull@kernel.org> Cc: Alex Williamson <alex.williamson@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Christoph Lameter <cl@linux.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Moritz Fischer <mdf@kernel.org> Cc: Paul Mackerras <paulus@ozlabs.org> Cc: Steve Sistare <steven.sistare@oracle.com> Cc: Wu Hao <hao.wu@intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
786 lines
19 KiB
C
786 lines
19 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/string.h>
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#include <linux/compiler.h>
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#include <linux/export.h>
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#include <linux/err.h>
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#include <linux/sched.h>
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#include <linux/sched/mm.h>
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#include <linux/sched/signal.h>
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#include <linux/sched/task_stack.h>
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#include <linux/security.h>
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#include <linux/swap.h>
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#include <linux/swapops.h>
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#include <linux/mman.h>
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#include <linux/hugetlb.h>
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#include <linux/vmalloc.h>
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#include <linux/userfaultfd_k.h>
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#include <linux/uaccess.h>
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#include "internal.h"
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/**
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* kfree_const - conditionally free memory
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* @x: pointer to the memory
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*
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* Function calls kfree only if @x is not in .rodata section.
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*/
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void kfree_const(const void *x)
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{
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if (!is_kernel_rodata((unsigned long)x))
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kfree(x);
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}
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EXPORT_SYMBOL(kfree_const);
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/**
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* kstrdup - allocate space for and copy an existing string
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* @s: the string to duplicate
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* @gfp: the GFP mask used in the kmalloc() call when allocating memory
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*
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* Return: newly allocated copy of @s or %NULL in case of error
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*/
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char *kstrdup(const char *s, gfp_t gfp)
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{
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size_t len;
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char *buf;
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if (!s)
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return NULL;
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len = strlen(s) + 1;
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buf = kmalloc_track_caller(len, gfp);
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if (buf)
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memcpy(buf, s, len);
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return buf;
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}
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EXPORT_SYMBOL(kstrdup);
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/**
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* kstrdup_const - conditionally duplicate an existing const string
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* @s: the string to duplicate
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* @gfp: the GFP mask used in the kmalloc() call when allocating memory
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*
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* Note: Strings allocated by kstrdup_const should be freed by kfree_const.
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*
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* Return: source string if it is in .rodata section otherwise
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* fallback to kstrdup.
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*/
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const char *kstrdup_const(const char *s, gfp_t gfp)
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{
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if (is_kernel_rodata((unsigned long)s))
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return s;
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return kstrdup(s, gfp);
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}
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EXPORT_SYMBOL(kstrdup_const);
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/**
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* kstrndup - allocate space for and copy an existing string
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* @s: the string to duplicate
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* @max: read at most @max chars from @s
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* @gfp: the GFP mask used in the kmalloc() call when allocating memory
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*
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* Note: Use kmemdup_nul() instead if the size is known exactly.
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*
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* Return: newly allocated copy of @s or %NULL in case of error
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*/
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char *kstrndup(const char *s, size_t max, gfp_t gfp)
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{
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size_t len;
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char *buf;
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if (!s)
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return NULL;
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len = strnlen(s, max);
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buf = kmalloc_track_caller(len+1, gfp);
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if (buf) {
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memcpy(buf, s, len);
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buf[len] = '\0';
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}
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return buf;
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}
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EXPORT_SYMBOL(kstrndup);
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/**
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* kmemdup - duplicate region of memory
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*
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* @src: memory region to duplicate
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* @len: memory region length
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* @gfp: GFP mask to use
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*
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* Return: newly allocated copy of @src or %NULL in case of error
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*/
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void *kmemdup(const void *src, size_t len, gfp_t gfp)
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{
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void *p;
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p = kmalloc_track_caller(len, gfp);
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if (p)
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memcpy(p, src, len);
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return p;
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}
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EXPORT_SYMBOL(kmemdup);
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/**
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* kmemdup_nul - Create a NUL-terminated string from unterminated data
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* @s: The data to stringify
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* @len: The size of the data
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* @gfp: the GFP mask used in the kmalloc() call when allocating memory
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*
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* Return: newly allocated copy of @s with NUL-termination or %NULL in
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* case of error
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*/
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char *kmemdup_nul(const char *s, size_t len, gfp_t gfp)
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{
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char *buf;
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if (!s)
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return NULL;
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buf = kmalloc_track_caller(len + 1, gfp);
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if (buf) {
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memcpy(buf, s, len);
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buf[len] = '\0';
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}
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return buf;
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}
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EXPORT_SYMBOL(kmemdup_nul);
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/**
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* memdup_user - duplicate memory region from user space
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*
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* @src: source address in user space
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* @len: number of bytes to copy
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*
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* Return: an ERR_PTR() on failure. Result is physically
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* contiguous, to be freed by kfree().
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*/
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void *memdup_user(const void __user *src, size_t len)
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{
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void *p;
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p = kmalloc_track_caller(len, GFP_USER | __GFP_NOWARN);
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if (!p)
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return ERR_PTR(-ENOMEM);
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if (copy_from_user(p, src, len)) {
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kfree(p);
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return ERR_PTR(-EFAULT);
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}
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return p;
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}
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EXPORT_SYMBOL(memdup_user);
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/**
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* vmemdup_user - duplicate memory region from user space
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*
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* @src: source address in user space
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* @len: number of bytes to copy
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*
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* Return: an ERR_PTR() on failure. Result may be not
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* physically contiguous. Use kvfree() to free.
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*/
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void *vmemdup_user(const void __user *src, size_t len)
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{
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void *p;
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p = kvmalloc(len, GFP_USER);
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if (!p)
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return ERR_PTR(-ENOMEM);
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if (copy_from_user(p, src, len)) {
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kvfree(p);
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return ERR_PTR(-EFAULT);
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}
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return p;
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}
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EXPORT_SYMBOL(vmemdup_user);
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/**
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* strndup_user - duplicate an existing string from user space
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* @s: The string to duplicate
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* @n: Maximum number of bytes to copy, including the trailing NUL.
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*
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* Return: newly allocated copy of @s or an ERR_PTR() in case of error
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*/
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char *strndup_user(const char __user *s, long n)
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{
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char *p;
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long length;
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length = strnlen_user(s, n);
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if (!length)
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return ERR_PTR(-EFAULT);
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if (length > n)
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return ERR_PTR(-EINVAL);
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p = memdup_user(s, length);
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if (IS_ERR(p))
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return p;
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p[length - 1] = '\0';
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return p;
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}
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EXPORT_SYMBOL(strndup_user);
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/**
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* memdup_user_nul - duplicate memory region from user space and NUL-terminate
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*
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* @src: source address in user space
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* @len: number of bytes to copy
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*
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* Return: an ERR_PTR() on failure.
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*/
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void *memdup_user_nul(const void __user *src, size_t len)
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{
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char *p;
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/*
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* Always use GFP_KERNEL, since copy_from_user() can sleep and
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* cause pagefault, which makes it pointless to use GFP_NOFS
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* or GFP_ATOMIC.
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*/
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p = kmalloc_track_caller(len + 1, GFP_KERNEL);
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if (!p)
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return ERR_PTR(-ENOMEM);
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if (copy_from_user(p, src, len)) {
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kfree(p);
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return ERR_PTR(-EFAULT);
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}
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p[len] = '\0';
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return p;
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}
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EXPORT_SYMBOL(memdup_user_nul);
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void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
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struct vm_area_struct *prev, struct rb_node *rb_parent)
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{
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struct vm_area_struct *next;
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vma->vm_prev = prev;
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if (prev) {
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next = prev->vm_next;
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prev->vm_next = vma;
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} else {
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mm->mmap = vma;
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if (rb_parent)
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next = rb_entry(rb_parent,
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struct vm_area_struct, vm_rb);
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else
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next = NULL;
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}
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vma->vm_next = next;
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if (next)
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next->vm_prev = vma;
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}
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/* Check if the vma is being used as a stack by this task */
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int vma_is_stack_for_current(struct vm_area_struct *vma)
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{
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struct task_struct * __maybe_unused t = current;
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return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t));
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}
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#if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
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void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
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{
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mm->mmap_base = TASK_UNMAPPED_BASE;
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mm->get_unmapped_area = arch_get_unmapped_area;
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}
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#endif
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/**
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* __account_locked_vm - account locked pages to an mm's locked_vm
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* @mm: mm to account against
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* @pages: number of pages to account
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* @inc: %true if @pages should be considered positive, %false if not
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* @task: task used to check RLIMIT_MEMLOCK
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* @bypass_rlim: %true if checking RLIMIT_MEMLOCK should be skipped
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*
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* Assumes @task and @mm are valid (i.e. at least one reference on each), and
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* that mmap_sem is held as writer.
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*
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* Return:
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* * 0 on success
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* * -ENOMEM if RLIMIT_MEMLOCK would be exceeded.
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*/
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int __account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc,
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struct task_struct *task, bool bypass_rlim)
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{
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unsigned long locked_vm, limit;
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int ret = 0;
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lockdep_assert_held_write(&mm->mmap_sem);
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locked_vm = mm->locked_vm;
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if (inc) {
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if (!bypass_rlim) {
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limit = task_rlimit(task, RLIMIT_MEMLOCK) >> PAGE_SHIFT;
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if (locked_vm + pages > limit)
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ret = -ENOMEM;
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}
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if (!ret)
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mm->locked_vm = locked_vm + pages;
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} else {
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WARN_ON_ONCE(pages > locked_vm);
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mm->locked_vm = locked_vm - pages;
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}
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pr_debug("%s: [%d] caller %ps %c%lu %lu/%lu%s\n", __func__, task->pid,
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(void *)_RET_IP_, (inc) ? '+' : '-', pages << PAGE_SHIFT,
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locked_vm << PAGE_SHIFT, task_rlimit(task, RLIMIT_MEMLOCK),
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ret ? " - exceeded" : "");
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return ret;
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}
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EXPORT_SYMBOL_GPL(__account_locked_vm);
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/**
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* account_locked_vm - account locked pages to an mm's locked_vm
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* @mm: mm to account against, may be NULL
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* @pages: number of pages to account
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* @inc: %true if @pages should be considered positive, %false if not
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*
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* Assumes a non-NULL @mm is valid (i.e. at least one reference on it).
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*
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* Return:
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* * 0 on success, or if mm is NULL
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* * -ENOMEM if RLIMIT_MEMLOCK would be exceeded.
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*/
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int account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc)
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{
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int ret;
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if (pages == 0 || !mm)
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return 0;
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down_write(&mm->mmap_sem);
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ret = __account_locked_vm(mm, pages, inc, current,
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capable(CAP_IPC_LOCK));
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up_write(&mm->mmap_sem);
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return ret;
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}
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EXPORT_SYMBOL_GPL(account_locked_vm);
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unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
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unsigned long len, unsigned long prot,
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unsigned long flag, unsigned long pgoff)
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{
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unsigned long ret;
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struct mm_struct *mm = current->mm;
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unsigned long populate;
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LIST_HEAD(uf);
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ret = security_mmap_file(file, prot, flag);
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if (!ret) {
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if (down_write_killable(&mm->mmap_sem))
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return -EINTR;
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ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff,
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&populate, &uf);
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up_write(&mm->mmap_sem);
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userfaultfd_unmap_complete(mm, &uf);
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if (populate)
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mm_populate(ret, populate);
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}
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return ret;
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}
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unsigned long vm_mmap(struct file *file, unsigned long addr,
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unsigned long len, unsigned long prot,
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unsigned long flag, unsigned long offset)
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{
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if (unlikely(offset + PAGE_ALIGN(len) < offset))
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return -EINVAL;
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if (unlikely(offset_in_page(offset)))
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return -EINVAL;
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return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
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}
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EXPORT_SYMBOL(vm_mmap);
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/**
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* kvmalloc_node - attempt to allocate physically contiguous memory, but upon
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* failure, fall back to non-contiguous (vmalloc) allocation.
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* @size: size of the request.
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* @flags: gfp mask for the allocation - must be compatible (superset) with GFP_KERNEL.
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* @node: numa node to allocate from
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*
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* Uses kmalloc to get the memory but if the allocation fails then falls back
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* to the vmalloc allocator. Use kvfree for freeing the memory.
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*
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* Reclaim modifiers - __GFP_NORETRY and __GFP_NOFAIL are not supported.
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* __GFP_RETRY_MAYFAIL is supported, and it should be used only if kmalloc is
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* preferable to the vmalloc fallback, due to visible performance drawbacks.
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*
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* Please note that any use of gfp flags outside of GFP_KERNEL is careful to not
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* fall back to vmalloc.
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*
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* Return: pointer to the allocated memory of %NULL in case of failure
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*/
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void *kvmalloc_node(size_t size, gfp_t flags, int node)
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{
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gfp_t kmalloc_flags = flags;
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void *ret;
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/*
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* vmalloc uses GFP_KERNEL for some internal allocations (e.g page tables)
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* so the given set of flags has to be compatible.
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*/
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if ((flags & GFP_KERNEL) != GFP_KERNEL)
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return kmalloc_node(size, flags, node);
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|
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/*
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* We want to attempt a large physically contiguous block first because
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* it is less likely to fragment multiple larger blocks and therefore
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* contribute to a long term fragmentation less than vmalloc fallback.
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* However make sure that larger requests are not too disruptive - no
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* OOM killer and no allocation failure warnings as we have a fallback.
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*/
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if (size > PAGE_SIZE) {
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kmalloc_flags |= __GFP_NOWARN;
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if (!(kmalloc_flags & __GFP_RETRY_MAYFAIL))
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kmalloc_flags |= __GFP_NORETRY;
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}
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ret = kmalloc_node(size, kmalloc_flags, node);
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/*
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* It doesn't really make sense to fallback to vmalloc for sub page
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* requests
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*/
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if (ret || size <= PAGE_SIZE)
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return ret;
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return __vmalloc_node_flags_caller(size, node, flags,
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__builtin_return_address(0));
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}
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EXPORT_SYMBOL(kvmalloc_node);
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|
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/**
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* kvfree() - Free memory.
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* @addr: Pointer to allocated memory.
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*
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* kvfree frees memory allocated by any of vmalloc(), kmalloc() or kvmalloc().
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* It is slightly more efficient to use kfree() or vfree() if you are certain
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* that you know which one to use.
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*
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* Context: Either preemptible task context or not-NMI interrupt.
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*/
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void kvfree(const void *addr)
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{
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if (is_vmalloc_addr(addr))
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vfree(addr);
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else
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kfree(addr);
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}
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EXPORT_SYMBOL(kvfree);
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static inline void *__page_rmapping(struct page *page)
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{
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unsigned long mapping;
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mapping = (unsigned long)page->mapping;
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mapping &= ~PAGE_MAPPING_FLAGS;
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return (void *)mapping;
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}
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|
|
/* Neutral page->mapping pointer to address_space or anon_vma or other */
|
|
void *page_rmapping(struct page *page)
|
|
{
|
|
page = compound_head(page);
|
|
return __page_rmapping(page);
|
|
}
|
|
|
|
/*
|
|
* Return true if this page is mapped into pagetables.
|
|
* For compound page it returns true if any subpage of compound page is mapped.
|
|
*/
|
|
bool page_mapped(struct page *page)
|
|
{
|
|
int i;
|
|
|
|
if (likely(!PageCompound(page)))
|
|
return atomic_read(&page->_mapcount) >= 0;
|
|
page = compound_head(page);
|
|
if (atomic_read(compound_mapcount_ptr(page)) >= 0)
|
|
return true;
|
|
if (PageHuge(page))
|
|
return false;
|
|
for (i = 0; i < (1 << compound_order(page)); i++) {
|
|
if (atomic_read(&page[i]._mapcount) >= 0)
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
EXPORT_SYMBOL(page_mapped);
|
|
|
|
struct anon_vma *page_anon_vma(struct page *page)
|
|
{
|
|
unsigned long mapping;
|
|
|
|
page = compound_head(page);
|
|
mapping = (unsigned long)page->mapping;
|
|
if ((mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
|
|
return NULL;
|
|
return __page_rmapping(page);
|
|
}
|
|
|
|
struct address_space *page_mapping(struct page *page)
|
|
{
|
|
struct address_space *mapping;
|
|
|
|
page = compound_head(page);
|
|
|
|
/* This happens if someone calls flush_dcache_page on slab page */
|
|
if (unlikely(PageSlab(page)))
|
|
return NULL;
|
|
|
|
if (unlikely(PageSwapCache(page))) {
|
|
swp_entry_t entry;
|
|
|
|
entry.val = page_private(page);
|
|
return swap_address_space(entry);
|
|
}
|
|
|
|
mapping = page->mapping;
|
|
if ((unsigned long)mapping & PAGE_MAPPING_ANON)
|
|
return NULL;
|
|
|
|
return (void *)((unsigned long)mapping & ~PAGE_MAPPING_FLAGS);
|
|
}
|
|
EXPORT_SYMBOL(page_mapping);
|
|
|
|
/*
|
|
* For file cache pages, return the address_space, otherwise return NULL
|
|
*/
|
|
struct address_space *page_mapping_file(struct page *page)
|
|
{
|
|
if (unlikely(PageSwapCache(page)))
|
|
return NULL;
|
|
return page_mapping(page);
|
|
}
|
|
|
|
/* Slow path of page_mapcount() for compound pages */
|
|
int __page_mapcount(struct page *page)
|
|
{
|
|
int ret;
|
|
|
|
ret = atomic_read(&page->_mapcount) + 1;
|
|
/*
|
|
* For file THP page->_mapcount contains total number of mapping
|
|
* of the page: no need to look into compound_mapcount.
|
|
*/
|
|
if (!PageAnon(page) && !PageHuge(page))
|
|
return ret;
|
|
page = compound_head(page);
|
|
ret += atomic_read(compound_mapcount_ptr(page)) + 1;
|
|
if (PageDoubleMap(page))
|
|
ret--;
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(__page_mapcount);
|
|
|
|
int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS;
|
|
int sysctl_overcommit_ratio __read_mostly = 50;
|
|
unsigned long sysctl_overcommit_kbytes __read_mostly;
|
|
int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
|
|
unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
|
|
unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */
|
|
|
|
int overcommit_ratio_handler(struct ctl_table *table, int write,
|
|
void __user *buffer, size_t *lenp,
|
|
loff_t *ppos)
|
|
{
|
|
int ret;
|
|
|
|
ret = proc_dointvec(table, write, buffer, lenp, ppos);
|
|
if (ret == 0 && write)
|
|
sysctl_overcommit_kbytes = 0;
|
|
return ret;
|
|
}
|
|
|
|
int overcommit_kbytes_handler(struct ctl_table *table, int write,
|
|
void __user *buffer, size_t *lenp,
|
|
loff_t *ppos)
|
|
{
|
|
int ret;
|
|
|
|
ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
|
|
if (ret == 0 && write)
|
|
sysctl_overcommit_ratio = 0;
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Committed memory limit enforced when OVERCOMMIT_NEVER policy is used
|
|
*/
|
|
unsigned long vm_commit_limit(void)
|
|
{
|
|
unsigned long allowed;
|
|
|
|
if (sysctl_overcommit_kbytes)
|
|
allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10);
|
|
else
|
|
allowed = ((totalram_pages() - hugetlb_total_pages())
|
|
* sysctl_overcommit_ratio / 100);
|
|
allowed += total_swap_pages;
|
|
|
|
return allowed;
|
|
}
|
|
|
|
/*
|
|
* Make sure vm_committed_as in one cacheline and not cacheline shared with
|
|
* other variables. It can be updated by several CPUs frequently.
|
|
*/
|
|
struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
|
|
|
|
/*
|
|
* The global memory commitment made in the system can be a metric
|
|
* that can be used to drive ballooning decisions when Linux is hosted
|
|
* as a guest. On Hyper-V, the host implements a policy engine for dynamically
|
|
* balancing memory across competing virtual machines that are hosted.
|
|
* Several metrics drive this policy engine including the guest reported
|
|
* memory commitment.
|
|
*/
|
|
unsigned long vm_memory_committed(void)
|
|
{
|
|
return percpu_counter_read_positive(&vm_committed_as);
|
|
}
|
|
EXPORT_SYMBOL_GPL(vm_memory_committed);
|
|
|
|
/*
|
|
* Check that a process has enough memory to allocate a new virtual
|
|
* mapping. 0 means there is enough memory for the allocation to
|
|
* succeed and -ENOMEM implies there is not.
|
|
*
|
|
* We currently support three overcommit policies, which are set via the
|
|
* vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting.rst
|
|
*
|
|
* Strict overcommit modes added 2002 Feb 26 by Alan Cox.
|
|
* Additional code 2002 Jul 20 by Robert Love.
|
|
*
|
|
* cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
|
|
*
|
|
* Note this is a helper function intended to be used by LSMs which
|
|
* wish to use this logic.
|
|
*/
|
|
int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
|
|
{
|
|
long allowed;
|
|
|
|
VM_WARN_ONCE(percpu_counter_read(&vm_committed_as) <
|
|
-(s64)vm_committed_as_batch * num_online_cpus(),
|
|
"memory commitment underflow");
|
|
|
|
vm_acct_memory(pages);
|
|
|
|
/*
|
|
* Sometimes we want to use more memory than we have
|
|
*/
|
|
if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
|
|
return 0;
|
|
|
|
if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
|
|
if (pages > totalram_pages() + total_swap_pages)
|
|
goto error;
|
|
return 0;
|
|
}
|
|
|
|
allowed = vm_commit_limit();
|
|
/*
|
|
* Reserve some for root
|
|
*/
|
|
if (!cap_sys_admin)
|
|
allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
|
|
|
|
/*
|
|
* Don't let a single process grow so big a user can't recover
|
|
*/
|
|
if (mm) {
|
|
long reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10);
|
|
|
|
allowed -= min_t(long, mm->total_vm / 32, reserve);
|
|
}
|
|
|
|
if (percpu_counter_read_positive(&vm_committed_as) < allowed)
|
|
return 0;
|
|
error:
|
|
vm_unacct_memory(pages);
|
|
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/**
|
|
* get_cmdline() - copy the cmdline value to a buffer.
|
|
* @task: the task whose cmdline value to copy.
|
|
* @buffer: the buffer to copy to.
|
|
* @buflen: the length of the buffer. Larger cmdline values are truncated
|
|
* to this length.
|
|
*
|
|
* Return: the size of the cmdline field copied. Note that the copy does
|
|
* not guarantee an ending NULL byte.
|
|
*/
|
|
int get_cmdline(struct task_struct *task, char *buffer, int buflen)
|
|
{
|
|
int res = 0;
|
|
unsigned int len;
|
|
struct mm_struct *mm = get_task_mm(task);
|
|
unsigned long arg_start, arg_end, env_start, env_end;
|
|
if (!mm)
|
|
goto out;
|
|
if (!mm->arg_end)
|
|
goto out_mm; /* Shh! No looking before we're done */
|
|
|
|
spin_lock(&mm->arg_lock);
|
|
arg_start = mm->arg_start;
|
|
arg_end = mm->arg_end;
|
|
env_start = mm->env_start;
|
|
env_end = mm->env_end;
|
|
spin_unlock(&mm->arg_lock);
|
|
|
|
len = arg_end - arg_start;
|
|
|
|
if (len > buflen)
|
|
len = buflen;
|
|
|
|
res = access_process_vm(task, arg_start, buffer, len, FOLL_FORCE);
|
|
|
|
/*
|
|
* If the nul at the end of args has been overwritten, then
|
|
* assume application is using setproctitle(3).
|
|
*/
|
|
if (res > 0 && buffer[res-1] != '\0' && len < buflen) {
|
|
len = strnlen(buffer, res);
|
|
if (len < res) {
|
|
res = len;
|
|
} else {
|
|
len = env_end - env_start;
|
|
if (len > buflen - res)
|
|
len = buflen - res;
|
|
res += access_process_vm(task, env_start,
|
|
buffer+res, len,
|
|
FOLL_FORCE);
|
|
res = strnlen(buffer, res);
|
|
}
|
|
}
|
|
out_mm:
|
|
mmput(mm);
|
|
out:
|
|
return res;
|
|
}
|