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ANDROID: disable page table moves when speculative page faults are enabled

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move_page_tables() can move entire pmd or pud without locking individual
ptes. This is problematic for speculative page faults which do not take
mmap_lock because they rely on ptl lock when writing new pte value. To
avoid possible race, disable move_page_tables() optimization when
CONFIG_SPECULATIVE_PAGE_FAULT is enabled.

Bug: 257443051
Change-Id: Ib48dda08ecad1abc60d08fc089a6566a63393c13
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Git-commit: 0f43357d37e4451cdc12a60895b6e4929a87adf7
Git-repo: https://android.googlesource.com/kernel/common/
[quic_c_spathi@quicinc.com: resolve trivial merge conflicts]
Signed-off-by: Srinivasarao Pathipati <quic_c_spathi@quicinc.com>
This commit is contained in:
Suren Baghdasaryan 2022-11-18 17:06:03 -08:00 committed by Gerrit - the friendly Code Review server
parent 51cfccaecd
commit 78035f7a50
1 changed files with 5 additions and 1 deletions
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6
mm/mremap.c
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@ -191,7 +191,11 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
drop_rmap_locks(vma);
}
#ifdef CONFIG_HAVE_MOVE_PMD
/*
* Speculative page fault handlers will not detect page table changes done
* without ptl locking.
*/
#if defined(CONFIG_HAVE_MOVE_PMD) && !defined(CONFIG_SPECULATIVE_PAGE_FAULT)
static bool move_normal_pmd(struct vm_area_struct *vma, unsigned long old_addr,
unsigned long new_addr, unsigned long old_end,
pmd_t *old_pmd, pmd_t *new_pmd)