[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20220901173516.702122-23-surenb@google.com>
Date: Thu, 1 Sep 2022 10:35:10 -0700
From: Suren Baghdasaryan <surenb@...gle.com>
To: akpm@...ux-foundation.org
Cc: michel@...pinasse.org, jglisse@...gle.com, mhocko@...e.com,
vbabka@...e.cz, hannes@...xchg.org, mgorman@...e.de,
dave@...olabs.net, willy@...radead.org, liam.howlett@...cle.com,
peterz@...radead.org, ldufour@...ux.ibm.com,
laurent.dufour@...ibm.com, paulmck@...nel.org, luto@...nel.org,
songliubraving@...com, peterx@...hat.com, david@...hat.com,
dhowells@...hat.com, hughd@...gle.com, bigeasy@...utronix.de,
kent.overstreet@...ux.dev, rientjes@...gle.com,
axelrasmussen@...gle.com, joelaf@...gle.com, minchan@...gle.com,
surenb@...gle.com, kernel-team@...roid.com, linux-mm@...ck.org,
linux-arm-kernel@...ts.infradead.org,
linuxppc-dev@...ts.ozlabs.org, x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: [RFC PATCH RESEND 22/28] x86/mm: try VMA lock-based page fault
handling first
Attempt VMA lock-based page fault handling first, and fall back to the
existing mmap_lock-based handling if that fails.
Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>
---
arch/x86/mm/fault.c | 36 ++++++++++++++++++++++++++++++++++++
1 file changed, 36 insertions(+)
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index fa71a5d12e87..35e74e3dc2c1 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -19,6 +19,7 @@
#include <linux/uaccess.h> /* faulthandler_disabled() */
#include <linux/efi.h> /* efi_crash_gracefully_on_page_fault()*/
#include <linux/mm_types.h>
+#include <linux/mm.h> /* find_and_lock_vma() */
#include <asm/cpufeature.h> /* boot_cpu_has, ... */
#include <asm/traps.h> /* dotraplinkage, ... */
@@ -1323,6 +1324,38 @@ void do_user_addr_fault(struct pt_regs *regs,
}
#endif
+#ifdef CONFIG_PER_VMA_LOCK
+ if (!(flags & FAULT_FLAG_USER) || atomic_read(&mm->mm_users) == 1)
+ goto lock_mmap;
+
+ vma = find_and_lock_anon_vma(mm, address);
+ if (!vma)
+ goto lock_mmap;
+
+ if (unlikely(access_error(error_code, vma))) {
+ vma_read_unlock(vma);
+ goto lock_mmap;
+ }
+ fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs);
+ vma_read_unlock(vma);
+
+ if (!(fault & VM_FAULT_RETRY)) {
+ count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
+ goto done;
+ }
+ count_vm_vma_lock_event(VMA_LOCK_RETRY);
+
+ /* Quick path to respond to signals */
+ if (fault_signal_pending(fault, regs)) {
+ if (!user_mode(regs))
+ kernelmode_fixup_or_oops(regs, error_code, address,
+ SIGBUS, BUS_ADRERR,
+ ARCH_DEFAULT_PKEY);
+ return;
+ }
+lock_mmap:
+#endif /* CONFIG_PER_VMA_LOCK */
+
/*
* Kernel-mode access to the user address space should only occur
* on well-defined single instructions listed in the exception
@@ -1423,6 +1456,9 @@ void do_user_addr_fault(struct pt_regs *regs,
}
mmap_read_unlock(mm);
+#ifdef CONFIG_PER_VMA_LOCK
+done:
+#endif
if (likely(!(fault & VM_FAULT_ERROR)))
return;
--
2.37.2.789.g6183377224-goog
Powered by blists - more mailing lists