Re: [PATCH 4.4 03/34] mtd: nand: gpmi: Fix failure when a erased page has a bitflip at BBM
On Wed, Mar 07, 2018 at 09:12:36AM +0100, Boris Brezillon wrote: >On Tue, 06 Mar 2018 21:22:30 + >Ben Hutchings wrote: > >> On Fri, 2018-03-02 at 09:50 +0100, Greg Kroah-Hartman wrote: >> > 4.4-stable review patch. If anyone has any objections, please let me know. >> > >> > -- >> > >> > From: Sascha Hauer >> > >> > >> > [ Upstream commit fdf2e821052958a114618a95ab18a300d0b080cb ] >> > >> > When erased subpages are read then the BCH decoder returns STATUS_ERASED >> > if they are all empty, or STATUS_UNCORRECTABLE if there are bitflips. >> > When there are bitflips, we have to set these bits again to show the >> > upper layers a completely erased page. When a bitflip happens in the >> > exact byte where the bad block marker is, then this byte is swapped >> > with another byte in block_mark_swapping(). The correction code then >> > detects a bitflip in another subpage and no longer corrects the bitflip >> > where it really happens. >> [...] >> >> This seesm to be a bug fix for commit bd2e778c9ee3 "gpmi-nand: Handle >> ECC Errors in erased pages". That's not in 4.4 so the bug fix is not >> needed, though it doesn't appear to do any harm. > >I wonder why the fix was backported to stable releases in the first >place. AFAICS, there's no Cc-stable or Fixes tag in the original >commit. It's probably something in the backport-to-stable process I'm >not aware of. It's an attempt to mine kernel commits for commits that should go into stable trees but were not marked as such. Thanks again for the review! -- Thanks, Sasha
Re: [PATCH 4.4 03/34] mtd: nand: gpmi: Fix failure when a erased page has a bitflip at BBM
Boris, Am Mittwoch, 7. März 2018, 09:12:36 CET schrieb Boris Brezillon: > On Tue, 06 Mar 2018 21:22:30 + > > Ben Hutchings wrote: > > On Fri, 2018-03-02 at 09:50 +0100, Greg Kroah-Hartman wrote: > > > 4.4-stable review patch. If anyone has any objections, please let me > > > know. > > > > > > -- > > > > > > From: Sascha Hauer > > > > > > > > > [ Upstream commit fdf2e821052958a114618a95ab18a300d0b080cb ] > > > > > > When erased subpages are read then the BCH decoder returns STATUS_ERASED > > > if they are all empty, or STATUS_UNCORRECTABLE if there are bitflips. > > > When there are bitflips, we have to set these bits again to show the > > > upper layers a completely erased page. When a bitflip happens in the > > > exact byte where the bad block marker is, then this byte is swapped > > > with another byte in block_mark_swapping(). The correction code then > > > detects a bitflip in another subpage and no longer corrects the bitflip > > > where it really happens. > > > > [...] > > > > This seesm to be a bug fix for commit bd2e778c9ee3 "gpmi-nand: Handle > > ECC Errors in erased pages". That's not in 4.4 so the bug fix is not > > needed, though it doesn't appear to do any harm. > > I wonder why the fix was backported to stable releases in the first > place. AFAICS, there's no Cc-stable or Fixes tag in the original > commit. It's probably something in the backport-to-stable process I'm > not aware of. It was auto selected by a stable script. Thanks, //richard
Re: [PATCH 4.4 03/34] mtd: nand: gpmi: Fix failure when a erased page has a bitflip at BBM
On Tue, 06 Mar 2018 21:22:30 + Ben Hutchings wrote: > On Fri, 2018-03-02 at 09:50 +0100, Greg Kroah-Hartman wrote: > > 4.4-stable review patch. If anyone has any objections, please let me know. > > > > -- > > > > From: Sascha Hauer > > > > > > [ Upstream commit fdf2e821052958a114618a95ab18a300d0b080cb ] > > > > When erased subpages are read then the BCH decoder returns STATUS_ERASED > > if they are all empty, or STATUS_UNCORRECTABLE if there are bitflips. > > When there are bitflips, we have to set these bits again to show the > > upper layers a completely erased page. When a bitflip happens in the > > exact byte where the bad block marker is, then this byte is swapped > > with another byte in block_mark_swapping(). The correction code then > > detects a bitflip in another subpage and no longer corrects the bitflip > > where it really happens. > [...] > > This seesm to be a bug fix for commit bd2e778c9ee3 "gpmi-nand: Handle > ECC Errors in erased pages". That's not in 4.4 so the bug fix is not > needed, though it doesn't appear to do any harm. I wonder why the fix was backported to stable releases in the first place. AFAICS, there's no Cc-stable or Fixes tag in the original commit. It's probably something in the backport-to-stable process I'm not aware of. Anyway, not an issues since the changes seems to be harmless. -- Boris Brezillon, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering https://bootlin.com
Re: [PATCH 4.4 03/34] mtd: nand: gpmi: Fix failure when a erased page has a bitflip at BBM
On Fri, 2018-03-02 at 09:50 +0100, Greg Kroah-Hartman wrote: > 4.4-stable review patch. If anyone has any objections, please let me know. > > -- > > From: Sascha Hauer > > > [ Upstream commit fdf2e821052958a114618a95ab18a300d0b080cb ] > > When erased subpages are read then the BCH decoder returns STATUS_ERASED > if they are all empty, or STATUS_UNCORRECTABLE if there are bitflips. > When there are bitflips, we have to set these bits again to show the > upper layers a completely erased page. When a bitflip happens in the > exact byte where the bad block marker is, then this byte is swapped > with another byte in block_mark_swapping(). The correction code then > detects a bitflip in another subpage and no longer corrects the bitflip > where it really happens. [...] This seesm to be a bug fix for commit bd2e778c9ee3 "gpmi-nand: Handle ECC Errors in erased pages". That's not in 4.4 so the bug fix is not needed, though it doesn't appear to do any harm. Ben. -- Ben Hutchings Software Developer, Codethink Ltd.
[PATCH 4.4 03/34] mtd: nand: gpmi: Fix failure when a erased page has a bitflip at BBM
4.4-stable review patch. If anyone has any objections, please let me know.
--
From: Sascha Hauer
[ Upstream commit fdf2e821052958a114618a95ab18a300d0b080cb ]
When erased subpages are read then the BCH decoder returns STATUS_ERASED
if they are all empty, or STATUS_UNCORRECTABLE if there are bitflips.
When there are bitflips, we have to set these bits again to show the
upper layers a completely erased page. When a bitflip happens in the
exact byte where the bad block marker is, then this byte is swapped
with another byte in block_mark_swapping(). The correction code then
detects a bitflip in another subpage and no longer corrects the bitflip
where it really happens.
Correct this behaviour by calling block_mark_swapping() after the
bitflips have been corrected.
In our case UBIFS failed with this bug because it expects erased
pages to be really empty:
UBIFS error (pid 187): ubifs_scan: corrupt empty space at LEB 36:118735
UBIFS error (pid 187): ubifs_scanned_corruption: corruption at LEB 36:118735
UBIFS error (pid 187): ubifs_scanned_corruption: first 8192 bytes from LEB
36:118735
UBIFS error (pid 187): ubifs_scan: LEB 36 scanning failed
UBIFS error (pid 187): do_commit: commit failed, error -117
Signed-off-by: Sascha Hauer
Reviewed-by: Richard Weinberger
Acked-by: Boris Brezillon
Signed-off-by: Richard Weinberger
Signed-off-by: Sasha Levin
Signed-off-by: Greg Kroah-Hartman
---
drivers/mtd/nand/gpmi-nand/gpmi-nand.c |6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
@@ -1029,9 +1029,6 @@ static int gpmi_ecc_read_page(struct mtd
return ret;
}
- /* handle the block mark swapping */
- block_mark_swapping(this, payload_virt, auxiliary_virt);
-
/* Loop over status bytes, accumulating ECC status. */
status = auxiliary_virt + nfc_geo->auxiliary_status_offset;
@@ -1047,6 +1044,9 @@ static int gpmi_ecc_read_page(struct mtd
max_bitflips = max_t(unsigned int, max_bitflips, *status);
}
+ /* handle the block mark swapping */
+ block_mark_swapping(this, buf, auxiliary_virt);
+
if (oob_required) {
/*
* It's time to deliver the OOB bytes. See gpmi_ecc_read_oob()
