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ARC: mm: fix leakage of memory allocated for PTE

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Since commit d9820ff ("ARC: mm: switch pgtable_t back to struct page *")
a memory leakage problem occurs. Memory allocated for page table entries
not released during process termination. This issue can be reproduced by
a small program that allocates a large amount of memory. After several
runs, you'll see that the amount of free memory has reduced and will
continue to reduce after each run. All ARC CPUs are effected by this
issue. The issue was introduced since the kernel stable release v5.15-rc1.

As described in commit d9820ff after switch pgtable_t back to struct
page *, a pointer to "struct page" and appropriate functions are used to
allocate and free a memory page for PTEs, but the pmd_pgtable macro hasn't
changed and returns the direct virtual address from the PMD (PGD) entry.
Than this address used as a parameter in the __pte_free() and as a result
this function couldn't release memory page allocated for PTEs.

Fix this issue by changing the pmd_pgtable macro and returning pointer to
struct page.

Fixes: d9820ff76f ("ARC: mm: switch pgtable_t back to struct page *")
Cc: Mike Rapoport <rppt@kernel.org>
Cc: <stable@vger.kernel.org> # 5.15.x
Signed-off-by: Pavel Kozlov <pavel.kozlov@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@kernel.org>
This commit is contained in:
Pavel Kozlov 2022-10-17 20:11:27 +04:00 committed by Vineet Gupta
parent 2df1f4a77b
commit 4fd9df10cb
1 changed files with 1 additions and 1 deletions
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2
arch/arc/include/asm/pgtable-levels.h
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@ -161,7 +161,7 @@
#define pmd_pfn(pmd) ((pmd_val(pmd) & PAGE_MASK) >> PAGE_SHIFT)
#define pmd_page(pmd) virt_to_page(pmd_page_vaddr(pmd))
#define set_pmd(pmdp, pmd) (*(pmdp) = pmd)
#define pmd_pgtable(pmd) ((pgtable_t) pmd_page_vaddr(pmd))
#define pmd_pgtable(pmd) ((pgtable_t) pmd_page(pmd))
/*
* 4th level paging: pte